This is a little after my time but I'll give it a go. Your first stop for reading should be Foner's Reconstruction. Get the new edition and Foner adds a forward reviewing historiography since 1988 up to about 2011. Beyond that, the main trends in major Reconstruction works since Foner have been to highlight the violence much more than he does and lately to challenge his position that Reconstruction is mostly about Civil Rights 1.0. The Unfinished Revolution in his subtitle is that. No one disputes that now, but I'm aware of a recent book that's more skeptical of white commitment to that project than Foner is.

So the questions.

1. Reconstruction is the effort undertaken by the national government to reintegrate the South into the nation and remake it in the image of the victorious section.

2. It depends what part of Reconstruction we're talking about. If it's preventing a decades-long guerrilla war among whites, then Reconstruction mostly succeeded. If it's preventing the same against black Americans, Reconstruction failed. If it's securing the freedmen's civil rights, then at first it made serious gains and then failed...or rather was allowed to fail in the face of tremendous violence. If it's removing the planters from control of Southern politics, then the record is mixed. If it's bringing industry to the South, then it did ok. Most people talking about Reconstruction are most interested in the rights of the freedpeople because their condition has been the centerpiece of both the traditional "Reconstruction is evil and it's tragic that it was tried" school and the newer "Reconstruction was noble and it's tragic that it failed" school.

3. It's huge. During Reconstruction, some whites were willing to attempt genuine interracial politics on a level we don't see again in the US until the 1960s. It's going too far to say that they generally think of black Americans as their equals, but general opinion of them among whites outside the South is about as high as it's going to get for a century. Once Reconstruction is allowed to fail, the faults of Reconstruction-era governments are all laid at the feed of the freedpeople and it spawns a whole new wave of arguments about black inferiority which quickly assume a more scientific gloss. This is roughly contemporaneous with European powers colonizing Africa on a large scale and the general height of white imperialism. The failure of Reconstruction is noted abroad and seized upon as further justification for empire.

Domestically the same thing shakes out. Reconstruction prevented -and was to some degree inspired by- attempts to restore slavery in every detail except the word itself in the form of the black codes. Then Washington progressively loses interest in fighting it out. This is happening as early as 1868, though there are partial reverses. Then ensues a long period where the US has divided government and the Democrats aren't about to permit any reconstructing considering their coalition rests on white rule and white terror in the South. By the time the GOP has united government again in the 1890s and it looks like they might come roaring back, it turns out that enough of the party has lost interest to prevent even minor gains.

Southern whites get right back to work. Exact dates for when we change over to Jim Crow vary place to place and by what metric one views as most important, but some black men are able to vote into the 1880s and into the 1890s there are still some who hold federal offices. The last Jim Crow Constitution (Mississippi's) doesn't roll out until 1905. By that time, few whites outside the South think it's worth a fight. The tremendous number of lynchings, many of them gory spectacles photographed for posterity, do more to convince them of inherent black criminality than of white cruelty and lawlessness.

I am finding some excellent information about Reconstruction in Ron Chernow's biography "Grant". Chernow posits that Grant has not been given enough historical credit for his efforts to implement Lincoln's (admittedly under-developed) vision for reconstructing the South. Chernow links Grant's generous terms of surrender offered to Lee at Appomattox as being perfectly in tune with Lincoln's desire for reconciliaion with the South. Grant was possibly the most pro-Civil Rights president between the time of Lincoln and FDR. During the Presidency of Andrew Johnson, Grant (as military chief over the entire South) actively went around Johnson's attempts to protect the White Southern ruling class and undermine efforts to provide aid and enfranchisement of Blacks. Grant also oversaw the destruction of the original KKK (not to be confused with the 20th century revised version of the KKK). But Grant's Presidency was undermined by corruption scandals and economic depression, which in turn undermined Grant's effectiveness in preventing the entrenchment of the Jim Crow laws.