is there any way to get a fancy suite like the one President Kimball has and without killing people or without loosing a reputation with the Strip or the NCR. and is there any place to find one or buy one, i dont mind killing anyone as long as i don't loose reputation from the Strip or NCR. And yes president kimball survived

The formal wear is an suit and you get one free if you join the White Glove Society. Note that you have to help Heck get his son back and expose Mortimer to be able to get the suit and that is what I consider the best option for the quest :disguise:

The people who stole Vance's gun. That dude has a fly suite. He should be in the Mess (?) hideout. North-west of new vegas. Its a little shack. You will have to kill them both, but you dont lose any karma or rep.