I know I'm a bit late on this but just thought I'd make my comments too
We got one of our cats from Battersea Dogs Home and they charged £40. When we were looking at a local rescue place they charged £60. Neither of them were donations, just flat charges. Given that it cost me £60 to get our kitten spayed and micro-chipped (let alone the vaccination costs) I don't think there's anything wrong in having a fee.
With regard to the home visit, we had one from the local rescue place. The man who came round said we could have an older cat but not a young one as we live on a busy road. It's not actually a main road, just the old road that used to get used and it's not that busy - but cars do speed down there. He also said that we would only be allowed to have a cat if we promised to never go out of the front door, we had to go out of the back door and round the side - so that the cats wouldn't be interested in the front door. I couldn't really understand this as surely any cat would just then follow us round the side! Besides, they're so inquisitive they're always going to investigate the local area - and whilst they don't like the noise of the road they are tempted by the field on the other side.
I understand that they have the best interests of the cat at heart but he didn't have any issues with the house, how we looked after our existing cats etc - in the end you can't tell a cat what to do but at least any cat we have will have a wonderful, loving home to live in for the time that they are with us. Also it's a bit annoying as I know of plenty of cats that have been run over on 20mph roads in quiet housing estates - if it's going to happen, then it's going to happen is the unfortunate fact.