IF...i trap nearby homeless cat to adopt, then what?

I can't take him/her into my apt building right away; a year ago the building was sprayed for fleas, with all the tenants out for the day.

And, rabies worries, feline leukemia worries, neutering...doubtful my vet take cat in same day.

And what if, after every test, or even days in my apt; can't just drop off cat where I found him/her...