Thank you, first of all for stepping up and taking this baby kitty in, if there were more people like you, the homeless cat problem would be drastically reduced. Many folks do not realize the very short and tortured life these animals live!
It's a big responsibility but I think that the joy he brings, if you can get past this, will be well worth your efforts.
Because I just saw your inquiry and you wrote weeks ago I am not sure if this information will help you or not but I thought it was worth a try.
Quite honestly, you will eventually need to get some help from a Vet, most likely antibiotics for the respitory problems, but in the meantime there are some things that you can do at home.
Lady Guinevere mentions some good ones that I will definately be trying on my steady stream of homeless kittens and cats.
Another one is to start supplementing the kitty's food with lysine in case she is suffering from the feline herpes virus. This is the most common reason for respitory problems in cats, that can go on to develop bacterial infections which is why you will eventually need some antibiotics from a Vet. For now though, the amino acid in lysine prevents the replication of the herpes virus. You can use a product made just for cats like Viralys or Enisyl-F (www.entirelypets.com). Or you can do what I did and use the tablets for people, available at the pharmacy & many grocery stores. The tablets are typically 1000 mg. so you will need to divide into quarters (250 mg. is enough for kitten) and then crush up and mix well into her food.
For the eyes, you can use a product called Terramycin eye ointment. (Try E-Bay) This will treat a broad range of bacterial infections and help protect and heal ulcers caused by the feline heprs virus. You will need to gently pull down bottom eye lid and place a 1/4" strip of the ointment in his eyes 3 times per day for about 10 days in most cases.
Because of the time lapse, you may be well beyond this stage so please feel free to share any updated concerns, milestones or questions. I have been through this and know how difficult it is to see an innocent sick creature and feel like there is nothing you can do about it, since veterinary care is so expensive.
Keep us posted and thank you for reaching out.