Is there a way to do DLC content and explore/finish side quests post-battle (chronologically), or does the Hoover Dam battle finish the game and all DLC/side quests take place before that (as in, you have to go back to a pre-Dam save to continue content).

Also, is thee a way to organize saves based on character, because I tried to make a second character and the saves got muddled in with the character I just used to finish the game.

First time finishing the FNV main story, sorry for silly questions.