When I was at the vets last week, just as I was leaving, a stray cat walked puposefully right in front of me and then parked himself under the ambulance. He was dragging his back leg really badly, and I thought what a smart guy to have come to the right place for treatment!

Anyway, the vets kindly said they'd treat him for free, and it turned out for the poor little guy that his leg was badly infected and needed amputating, which happened last night. He's going to stay there and recover for the next couple of weeks, then he's going to be neutered. Vet was planning to do it at the same time as the amputation, but said he lost a lot of blood and was becoming too weak, so she had to finish up. I went to see him today and he's a little cutie

but he's still very sore from the operation, and by all accounts just a little aggressive. But so would I be if someone had just cut my leg off without asking

- so I don't want to make any judgements about his character until he's both neutered and recovered from the amputation.
After that, unless someone adopts him, they're going to put him back outside

and 'hope' that he sticks around, as if he does, they'll look out for him. But since he's only got 3 legs, he's probably not going to survive for long on the street again. He wasn't doing at all well before he turned up, and it's surprising he wasn't hit by a car, since he was only basically using 3 legs anyway.
The thing is, I'm willing to foster him but I can't adopt (I already have 4 cats!) but I have a couple of people in mind who might be interested in adopting, but they also already have cats (and dogs). So I need to know (as would they) that he hasn't got anything he could pass on to my cats first, so my question is, what things do I need to get him tested or inspected for? I have a small list already (fleas, earmites, ringworm, worms, feline leukemia) but what else could other cats be at risk of? There's still time, because I'm not going to foster him until he's recovered and neutered, so that's a couple of weeks away, and I would keep them separated for quite a while anyway. I'm going to see him again on Monday after work, and am already looking forward to it
Any suggestions much appreciated!