How did the British management of the Mandate of Palestine affect the later formation of the proposed partition of 1948? Having read (or maybe misread), it appears the British were already separating and declaring various areas as being individually Jewish or Arab. If that is the case, how was it reacted to by all sides? If I misread and the Jewish and Arab people did this themselves then how did the British handle this?

Good question! As a preface, the partition was proposed and voted on in 1947, not 1948.

So, the British management had a huge effect, in general. The British choices, like denying the Arabs an effective and representative management from the start of the Mandate, kept many Arabs fragmented. What administration they did get upset the order of the Ottoman rule that people had been used to. As Khalidi puts it:

There previously had been a mufti (scholar of recognized authority to deliver interpretations of Islamic law) of Jerusalem, which had always been an important post in the past, but one both limited both in terms of geographical scope and authority to the city of Jerusalem. In the Ottoman and every other Islamic system, the post of mufti was always clearly subordinate in power and prestige to that of the qadi (or judge). The qadi was appointed by the Ottoman state from the ranks of the official Ottoman religious establishment, and almost never came from a local family. The mufti, as well as the qadi’s deputy, the na'ib, who was also chief secretary of the Sharia court, were by contrast always local officials. This existing system was completely restructured by the British, who effectively placed the mufti above all other religious officials in Palestine.

This was crucial to effectively changing the way it turned out, especially since the familial control led to fractured groupings among the Palestinian Arabs, which persisted throughout until the partition and kept them much less organized, and made it harder for them to lobby. The Zionist organizations that kept the Yishuv focused on its goal were not reciprocally used by the Arabs, because of this upset order. As Smith describes:

Disagreement arose as to what policy to pursue with respect to the British and Zionism, with differences often reflecting the status of one's family before the war. The al-Husayni family, for example, controlled in 1918 the two most important posts in the Jerusalem administration: Musa Kazim al-Husayni was mayor and Kamil al-Husayni was mufti, the chief legal official of the Muslim community. Both, but especially Kamil, welcomed British rule and cooperated with the administration in its early stages. Both opposed Zionism but recognized that their own positions of prominence were not threatened by the British assumption of power. It was through them and members of other notable families that the Muslim-Christian Association was founded in November 1918.

The famous rivalry between the al-Nashashibis and al-Husaynis led to fragmentation within the Palestinian movement, and this was exacerbated thanks to the way the British organized the Arab system.

Now, the British were not actively (from my understanding) attempting to separate communities. Far more often, there was a process of self-segregation, especially thanks to the Zionists. Hoping that proving they could work an economic miracle in the area, and be self-sufficient in their economy, the prominent Labor Zionists were at first split over whether or not to exclude Palestinian-Arabs from their economy, going so far as to try to only hire Jewish laborers. The fight, which was held by the Histadrut (who hoped to force hiring only "union workers" who were Jewish) was done because the groups making up the Histadrut (the powerful worker's organization of the Jews, arguably the most powerful group in the area) were both in favor of the idea that Zionism would be powerless if it didn't rely on Jewish investment, labor, and capital. The modernity of the Jewish settlements that the UN Partition Plan committee saw was a result of this self-segregation, and while the rising economy did help Palestinian-Arabs, they still had significantly less industry and growth, due to the internal divisions and lifestyles accustomed more towards communal farming. The British didn't seem to deal with this much: they were mostly in favor of a Jewish state anyways. There were a few notable exceptions where they made an about-face, like when they attempted the 1939 White Paper that restricted Jewish immigration and offered a Palestinian-Arab state in 10 years if circumstances permitted, or when they were under the Atlee government which took over from Churchill in 1945, which was more inclined to support the partition plan. However, even that support was conditional, as the British wanted the Negev to go to the Arabs, not to the Jews.

Following the proposal of the three sided partition of Israel following WWII (Jewish and Arab state, and a " Special International Regime for the City of Jerusalem"), the Arabs/Palestinians did not agree with the suggested plan, claiming it went against their UN mandated rights to self-determination.

What were the actual politics of the Palestinians regarding this issue and how much did religion play a part in their rejection of this plan? How accurate is the statement that most of their rejection came from this violation of self-determination? If accurate, does it even play a role in Palestinian arguments anymore?

Well, there's a lot to talk about, but the politics of this was a mostly unilateral no. The leaders, including the aforementioned Mufti (now Hajj Amin al-Husayni, who had been exiled by the British and worked with the Nazis during WWII) and his family led much of the organized movement of the Palestinians at the time. They were opposed to any Jewish state in the area, and mobilization plans in case of partition passing in the UN were prepared before the fighting actually began. Religion absolutely played a part, as it has in the entire conflict since (though it's not the only, or necessarily the most important part). The idea of losing sovereignty and/or custodianship over the holy sites, including the Haram al-Sharif, to an international regime, was not particularly enticing to them. This plan has been put forward since to the Palestinians, but was again rejected. The fear that the Jews would somehow find a way to rebuild the Third Temple on the remains of their holy sites (and take the sites down, of course) was very prominent, even with the partition plan proposal.

There was also an idea of self-determination, and broken promises. The Arabs had, from the start, expected their state would include Palestine. The McMahon Correspondences in 1915 had seemed to promise this, though the British would later use semantics over the word district to get out of it, if memory serves. The feeling that they were natives, and that the League of Nations called, after all, for self-determination by the population in Article 22 of the League of Nations Charter:

Certain communities formerly belonging to the Turkish Empire have reached a stage of development where their existence as independent nations can be provisionally recognized subject to the rendering of administrative advice and assistance by a Mandatory until such time as they are able to stand alone. The wishes of these communities must be a principal consideration in the selection of the Mandatory.

Now, this obviously is vague, and the British used that to their advantage. But the feeling of nationalism did not falter or fail, and while it had begun more as a pan-Arab movement (hoping to be a part of Greater Syria), the movement eventually shifted to an independent Palestinian-Arab state, especially noted in the prominent newspapers of the time in the area, like Filastin (the name says it all). I cannot comment on the role this plays today, and I will not take sides on the issue. The commitments are, as I noted, vague and were argued. The British policies did not solve the conflict, and arguably made it worse, but they were (at least, in my opinion) made to both sides with intent to do something more urgent than anything else: win WWI (and later, WWII). In that context, it's understandable that the British were thinking "promise now, handle later", though they did devote considerable thought and energy to these plans anyways, underestimating the conflict's eventual growth and then underestimating the tenacity of those involved.

What was meant by a " Special International Regime for the City of Jerusalem"? Was it meant to be a neutral city where the other two states had representation? Was it just to keep a watchful eye on the situation? If so, how was this not likened to a continuation of colonialism despite countries starting to back out of the practice?

Well, it's difficult to give a comprehensive answer. The best way to look at it is obviously to read the partition plan at Part III. The idea was to have the Trusteeship Council supervise the eventual transition of authority out of the British hands, have it decide how the city would be administered (procedures, picking a governor who was not a member of either state in Palestine, etc.). The idea was to have a third party administer it who had no bias, and keep both sides having local autonomy where possible, and otherwise just being forced to live in harmony. If neither of you could decide who gets it, the idea goes, then neither of you will, and someone will handle it for you. Countries weren't intending to "rule" the area, it was meant to just be an unbiased solution. Every 10 years it would be reassessed, with hearings and referendums if necessary, and people would talk about if they wanted to change: ie. If you guys don't come to an agreement in 10 years, we'll have to wait another 10 with no one getting it.

Continued below.