First of all, boone won't speak to me because i don't have the right credentials fo the ncr? How do i solve this easily?

Also i met a women with alot of dogs, she attacked me on sight so i had to kill her. When i looted the body's i apparantly took her head and brains. Turns out they are now stuck in my inventory because they are related to a quest; they are quest items. What quest is she related to, how do i solve this?

I know Violets head is turned in at the local NCR base West North west of where you killed her, the dogs brains I am not sure of yet. There are 2 other Fiend's to kill for the heads, Cook-cook and Driver. Driver is just south of the rock crushing plant and cook-cook is in a crushed building just south of violet. Make sure u do not shoot them in the heads or you can not complete the bounty quest on them.

Her head is required for a bounty quest given by Major Dhatri at Camp McArran. The brain (I assume you actually mean the brain from one of her dogs) is used in a quest to repair a cyberdog.

I hope since i have these items before i accepted any quests, that those quests are still able to be activated?

Also about boone, how do i get in in favor, what to do specific?

The dog's (Violetta, not Violet, or vice versa, can't remember) brains are for the companion quest with Rex. You'll get a quest related to him. There is also an option to get a dog brain from the Legion, and I'm assuming this dog is named as well. Violetta's brain allows for a movement speed buff on Rex. Not sure what other options there are as movement speed seemed just about right for him.