Awww!!! No matter what, if you end up keeping him or finding him a good home, thank you for bringing him in from the rain and feeding him. He is still young enough and super cute, so hopefully you can find him a good home soon. What a lucky little fella he is right now just to be warm.
Btw, I have a third cat. I did not want a third cat. I had two cats, and that was my limit, and I have a big dog. My last little kitty found me almost 1 year ago, and we took him in to foster him and find him a good home. Well, he ended up purring and non stop cuddling into our necks and we fell madly in love with him. We now have three cats. I have to tell you, it was not that much harder to have three than two, but that would be provided they all got along with each other.
Good luck no matter what you decide. He is very adorable.