3- Where would they get electricity. F3 had no power source.
New vegas might have them. but i doubt they would choose to power street lights with the power from hoover damn. they would probably save it for important settlements or NCR Outposts
Without having to power multiple counties and areas, Hoover
Dam should provide more than enough power to provide electricity to everything with more left over to spare. Basically, if the event of an apocalypse where people stop showing up to work in power factories, Vegas one of the best places to be in the world if you still want to plug in those kitchen appliances.
I hope not all Raiders are immediately 'feral'. I understand there being roaming gangs of raiders like we see in A Boy and His Dog, or Road Warrior, or the Book of Eli, that attack on sight. It would be nice to have them at least attempt to rob you first, however, much like the highway robbers would in Oblivion. Something to give you the chance to hand over items or weapons to avoid combat, or bluff, or intimidate, etc. I hear that disguises actually work for most of the factions in New Vegas, like being able to pass for NCR by wearing ranger armor, and vice versa. It would be awesome be able to dress like a certain raider group and get left alone unless you get too close to them.
For organized raiders, it would be neat for them to have established bases where you could meet with the leader and make a deal to go unmolested, or be able to wipe them out, preventing you from encountering that particularly gang for a certain amount of days or weeks in the game.
And for goodness sakes, I hope not all raiders find rotting corpses as acceptable interior decorating. I don't care how evil or crazy I am, I wouldn't sleep in the same room as bloated bodies. And if I happened to be part of a cannibal raider gang, I would keep that crap in the fridge, know what I'm saying?