Ghouls, the ammount of times my evil, selfish, horrible, disgusting morally and ethically loathsome characters have become saints by defending themselves from ghouls ughhh.
Level eight? you should be just by the Mojave outpost if at that level, if this is your first playthrough, head north to the police station then west a bunch of lowish level ghouls there.
Also powder ganger respawns near Goodsprings, donate to the followers at the mormon fort at later levels, and generally be nice to people.
You mean your reputation? I'm still figuring this out but when you do something for a faction, say the Boomers, it flashes up on the screen 1/5. Then the next thing is 2/5. I think your reputation progresses to Idolized when you reach 5/5? Is this right...can anyone else clear this up?
The 1 -5 mark is just a mini achievment thing, for every 5 quests / achievements you complete you get 80? XP as a reward.
Faction gain is unmarked as far as I can tell, just pop ups occur if enough is gained or lost.