Luckily where I live, there aren't any stray cats or at least I haven't seen any, all the cats I have seen have collars and are well fed and have homes.
However around my mum's there is a gang of about 5 cats that take it in turns and eat Doris' (my mums cat) left overs, which as she's a 16 year old fuss pot is quite a lot sometimes!
I'll try and get some pictures of them next time I'm there.
I think as long as you show compassion to strays and give them some attention and a bit of food they pretty much survive reasonably well.
There was one cat a black and white long haired cat we called Whitey that came around my mums for about 5 years and we fed her every day. At the time we didn't know it was a girl.
Unfortunately, she was out the front garden and a pit bull came along and savaged her. We put her in a box, I had a look and she was covered in blood and I instantly knew she was badly injured. I took her to the vets and the RSPCA kindly paid for her fee to be put to sleep. She had had her rib cage crushed and her stomach was badly severed and ripped. So I had to sign a paper for her to be put to sleep which was very heartbreaking.
But I'm glad that she was out our garden and we fed her all that time, cause we did grow to love her, and we were very sad when she died.
I will dig out a picture of her and post it as a tribute