I adopted my 3 cats from the feeding station I manage. They were already neutered.
Two of them just followed me home and refuse to leave, the third I adopted because she really suffered in the streets. She doesn't go out. The other 2 accompany me each night to feed the strays, and on weekends we take a longer stroll around the block, which is full of greenery and trees. As time goes by and they become older and more pampered, they show less desire to go outside, which is good. Rescuing these cats has been the most rewarding experience of my life.
As to litter box, they didn't require any training. The first time they just walked around till they found the litter boxes, used them and covered the stuff, very naturally. I wasn't even around. When we're outside, they wait till we're back home to use the toilet, even if they need to badly. They hate having to go outside the house, because it's not as safe.
All that said, I adopted the 3 cats that seemed most in tune with humans from the whole colony. I have no idea what it would be like with the cats that are more feral.
The Royal von Meouw Dynasty: His Royal Highness the late Prince von Meouw,
Her Royal Highness Princess Gatita von Meouw, Nikita Duchess of Meouw and
His Highness Cuchi-Cuchi, next in line for the throne of Prince von Meouw.