Question: Django sneaks back into Candyland at the end of the movie, but the only residents that show back up are Candie's closest people from the funeral. Did that mansion not just have a bunch of dudes capture Django in the shootout in the few scenes prior? Where are they now, or were those the men that Django killed in that cabin?
Question: Do Django and his wife finally get free, or they have to hide from other bounty hunters?
Answer: Since the film ends with their riding off together after blowing up Candieland, any answer would be speculation. Obviously, it's meant to be a happy ending, our conquering hero triumphantly riding from the scene of his victory over Candie and all his racist minions. Realistically speaking, of course, there would obviously be a huge price on Django's head after the carnage at Candieland, and they are fugitive Black people in the pre-Civil War Deep South; every single bounty hunter and law enforcement officer, not to mention just everyday racist yokels who hear about a giant payday, would be looking for them. In the real world, they would likely be apprehended within days, if not hours. So, maybe it's best not to think too much about what happens next.
Question: Why would Schultz and Candie risk their lives, and the lives of everyone around them, over a handshake?
Answer: Schultz finds Candie to be a vile human being and being forced to shake his hand to seal the deal is just too much for him to accept. Candie never had any idea that Schultz would shoot him so he's not really risking anything in his mind. Candie is simply gloating over his opponent.
Question: Is there any reason James Remar was hired to play two different unrelated characters?
Answer: I think the only reasonable explanation is because he's done it before... crappy answer but it's the only answer I could find online.
Answer: There were indeed a lot of people there for the shoot-out, and Django did kill many of them, but it's safe to assume that whoever was left alive was told to clear out of the mansion after the funeral, so that Candie's sister and close family could grieve in private.