sad story with a (hopefully) happy ending

[JessiSatts]

I had a cat and a dog when my parents divorced. Both animals lived mainly inside with us. When my dad re-married, my stepmom kicked both animals outside. Well, my dog didn't survive it for very long and when we had her put to sleep, she was in a horrible condition. The cat is a mancoon and is supposed to be fluffy and stuff. She's lost alot of fur and has gotten really skinny. I feel so bad for the cat. Keep in mind that she is about 8 yrs old and she's been outside for about 3 yrs now. Recently, I decided to move to my mother's house for the summer. I want to take Fluffy with me so she can spend her last few years nicely instead of like Niki (the dog), miserable.
I need to know what I need to do. She hasnt had vaccinations for a long time, I can't even remember the last time she went to the vet. She used to be litter trained. Is it still possible for her to be litter trained again evenh though she's been outside for a considerable amount of time and is an older cat? I would greatly appreciate any tips or information that anyone has for me. Thank you very much.