MeatyRichard

Ok then since I have nothing better to do: Jennifer Hale is in her room still. Eric is in the upper quarters where the Sgt. is and his sister girlfriend is in her room ( Eric will say directions). You will meet Ben on your way out. Of course I am assuming you did the athlete branch.

What do you exactly mean by kids?

Have you tried killing and resurrecting her using console commands? I don't know if it will work but might be worth a try. Maybe I am wrong and it is useless but it cant do any harm.

The point of no return is the (second) battle at Hoover Dam, you will get a prompt that will say that it is that way for whatever quest line you are doing. But, to answer your question more directly yes you can go the DLCs after that particular quest.

There is a way to make companions wear armor with less DT than their own by removing it with console commands. There is a video of it here: http://www.youtube.com/watch?v=BZgKjXjNBlE If that is not what you wanted my apologies. Oh, you dont need a mod for this, you can access console commands with the "~" button in case you did not know