Just wondering what the purposes was of helping that one Paladin to become the new elder... I helped him... Now he just says that he has a lot to do but to come back later and we will talk... I came back quite a bit later and he still says the same thing and the other elder is still in power.
*OK SPOILER*
If you keep the current elder in place do all his quest, side with the ncr, instead of blowing up the BoS bunker talk to the elder and he will ally with the NCR in the final battle. If you get the elder replaced by that head paladin you will not get them for allies in the final battle you wont be able to even get the dialog box for it.
If your out for yourself you can just tell yes man to ignore them or you can take care of them yourself but you no longer get to have the armory to sell you items if you blow them up/go on a killing spree.
House I do believe you have to kill everyone regardless...
Cezar no clue I cannot bring myself to help them....
Benny not sure if you can really side with him or not to take over vegas have not tried yet....