I am Turkish too so it may not be fair that your questions are answered in detail by me and me alone. So any additional comments are welcome. But I might give some factual information with regard to your questions and since they are facts alone (whenever possible), with very limited commentary, they may hopefully be perceived as objective. Interpretations on the issue are often problematic, motivated or biased by political commitments as well as concerns for funding, so even as a historian, I am sceptical towards much of scholarship (pro or anti-Armenian likewise). That is a sad thing to say, but the truth nevertheless.

1- I tend to think of this as a vicious cycle. The most significant and earliest anti-Armenian massacres before 1915 were in the mid-1890s when Abdulhamid II organised local Turks and Kurds into 'Hamidian regiments' to deal with Armenian insurgency. Things got out of hand and many Armenians were killed. From the mid-1890s onwards, things tended to go worse; 1909 Adana massacre, 1915... It should not be forgotten though that the Committee of Union and Progress actually enjoyed the support of politicised Armenians when they overthrew the autocratic rule of Abdulhamid II in 1908, and they tried energetically suppressing massacres in Adana in 1909 and punished Muslim leaders in the region for committed atrocities. But an Armenian nationalist group called Armenakan was founded in Van, Eastern Ottoman Empire, in 1885, a much larger group known as Hunchaks was founded in Switzerland in 1887, and Dashnaksutyun was founded in 1890 in Tbilisi, then part of the Russian Empire. So, there were active Armenian groups even before the 1894-96 Hamidian massacres. How strong were these? It is still a subject of debate but I will turn to this when answering your fourth question. For now, it suffices to say that while there were disagreements within these groups, none of them was merely intended as a group representing Ottoman Armenians interests in a unitary Ottoman land.

2- Yes. A group of Armenian militias led a punitive expedition in 1897 against Kurds in Khanasor. These Kurds had joined in the Ottoman Army in suppressing the Armenian revolt (and killing innocents?) in the city of Van during the Hamidian massacres. During the Balkan Wars (1912-13), several Armenians such as Garegin Nzhdeh and Andranik Ozanian joined the Bulgarian Army and helped form an Armenian volunteers' corps to fight against the Ottoman Army. Ironically, the minister of foreign affairs of the Empire back then was an Ottoman Armenian himself, Gabriel Noradunkyan Efendi. I think this captures how complicated matters of national identity can be and how people do not all of a sudden convert into a separate national identity. The Balkan Wars were notorious for the violence aimed against civilian Muslims; you may check Lev Trotsky's series of articles on the Balkan Wars, he also talks about Ozanian there. His account is quite rich in details about atrocities though I am not sure if he has anything in particular about Armenian corps on this matter. There are also other, individual attacks such as the Ottoman Bank robbery/shooting in 1896, the attempted murder of Abdulhamid II by bombing a mosque during his visit in 1905 (the Yıldız assassination attempt). There are other examples too and there were clashes between local Muslim and Armenian groups in 1915.

3- There are numbers. But here is an interesting thing. We have numbers about the population of Armenians in the Ottoman Empire and we can theoretically use them to understand how many Armenians were killed in 1915. In practice, this does not work at all. Estimates start from around 50.000 (false) and reach numbers exceeding the total number of Armenians in the Empire (false). For Turks and Kurds, we do not even have such a yardstick as the total number of Turks and Kurds in those regions. So I think numbers do not matter in any case. Consider there was only one civilian and innocent Armenian or Turk or Kurd who died in 1915 and suppose it was your grand-grandfather. Morally and metaphysically devastating enough, without having to concoct a race of numbers.

4- This is one of the major points of informed (but still political) debate. Any sensible historian cannot or at least should not deny two facts. There was active, armed Armenian revolutionary groups active in and out of the Empire enjoying some Russian and Allied support in 1915, and these groups were not as strong as an army at all. Were these groups strong enough to militarily defeat the Ottoman Army? I do not think so. But, then again, is the point of armed resistance really defeating the army militarily in such settings? There are situations like Vietnam, but for every Vietnam, there is more than one Greek independence, where the international intervention forced Ottomans to recognise the independence of Greece. The same point applies to Serbia, Bulgaria. This does not mean these people did not do anything for their independence, obviously, but this means thanks to British, French, Russian interventions they could defeat the Ottomans diplomatically without having to defeat them militarily. Resisting and surviving for long enough could bring benefits. The point of Armenian resistance was most likely the latter; I do not think many of them really aimed to defeat the Ottoman Army militarily and obtain independence or autonomy thus. On top of all these, consider the fact that the Armenian population in the Empire was not homogenous at all. During the independence of Greece, good portions of the land that became independent were already Greek dominated; the number of Turks in the Peloponnesian peninsula was negligible (not so in Greek Macedonia until the Balkan Wars though). There were Armenian-majority places especially in the Eastern parts of the Ottoman Empire, but nearly nowhere did Armenians enjoy unchallenged demographic domination. If there is an Armenian majority village in Van, for instance, the chances are that the very next village had a Muslim majority. In a setting like this, it is extremely difficult to succeed in armed rebellion, especially considering the fact that Armenian revolutionaries faced armed opposition from local Kurdish and Turkish forces before the state. Considering all these, the aim of Armenian revolutionaries were something like independence built on the Balkanian model described above. As before, there were Armenian groups that were active whose goal was holding up and assuring military and diplomatic support from the Allies. How strong or active were these? Armenians were no Assyrians with no armed resistance and nearly no popularity abroad. Nor were they potent enough to overthrow the Ottomans by themselves. The answer lies somewhere in between. As you speak Turkish, I will refer you to official documents of the Empire so that you can get an idea. Go to katalog.devletarsivleri.gov.tr and create a free account or log in. Search 'Mahmudiye Ermeni' and check the sheer number of reports and documents you will access. You can read their titles which are like summaries and if you read Ottoman Turkish you can also see original documents in scanned form. These are documents pertaining to activities of Armenians in Mahmudiye town in Van, modern-day Turkey; a city that was home to a sizeable Armenian population before 1915. You can try anything through basic search to get an idea about Armenian activities in any region, just try 'Istanbul Ermeni' if you wish. These are not the whole of documents, of course.

A final note. I would kindly ask anyone to consider the thought experiment about your grand-grandfather being the only killed person. This is very important morally, I believe. The questions of 'who threw the first stone' and 'who killed more?' overlook this. I have tried providing historical information but notice that even if one innocent person was killed, that and that alone is something that is morally unacceptable. If you wish to overlook the moral aspect, then all deaths are nothing but statistics.

Sources:

Louise Nalbandian, The Armenian Revolutionary Movement: the Development of Armenian Political Parties Through the Nineteenth Century (Berkeley: University of California Press, 1963). The information in this book shows the formation and development of Armenian nationalist movements within and beyond the borders of the Ottoman Empire. The usual caveats about objectivity obviously apply, but it contains important factual information about such groups. From my personal experience, I can say it was informative, even most Turks who are naturally taught more about Armenian separatism before 1915 (for obvious reasons) would not know the extent of Armenian political activity.

To Kill a Sultan: A Transnational History of the Attempt on Abdulhamid II (1905), ed. by Houssine Alloul, Edhem Eldem, Henk de Smaele (London: Palgrave Macmillan, 2018). This edited book is on the attempted assassination of Abdulhamid II in 1905. Relevant to the context, it provides important information about the organisation of Armenian revolutionaries and their connections with European revolutionaries.

I would also recommend anyone who speaks Turkish to use the archives linked above. It justs details reports about movements of Armenian armed groups in a certain region, but you can search other information as well. It is always nice to be able to see some original documents!