Sorry you guys are struggling with this. My son, who is 5, spent the last couple of years in a play based preschool. He wasn't really ready for K this year, but was ready to move on from his preschool. One of the options I considered was a Waldorf school because I felt it would meet many of his needs (for play, nature, outdoor time). I did know it wouldn't meet one big need of his - his desire to learn more academic things. So, I ended up choosing a Montessori school because he was beginning to figure out math and reading concepts on his own, but wanted a deeper understanding than would he could work out by himself. Even though the philosophies are different, it was a hard choice to make.
I used to teach Kindergarten and did Montessori training...
As far as teaching reading, I would get some phonemic awareness books. Phonemic awareness has to do with hearing the sounds in words (like a pre-runner to phonics - which would have more to do with recognizing the written symbol and correlating sound to it). There are some good books out there with fun activities/games you can do together. Also, I think a mix of phonics and reading together is great. I would also get really, really easy beginning readers. Starting to recognize words and patterns is an important part of figuring out the code that is reading. You can also use "baby" books for this purpose if your son is OK with it (doesn't feel like he is being made a baby). The kind of books that have one word per page that corresponds with the picture. A good teacher supply store should have all of these things.
As for math, I would make sure he understands quantity (he can count out how many objects are in a group), then symbol (he recognizes the numbers) and then help him correlate the two. Other typical K math concepts are measurement, time, very simple addition/subtraction. Again, a teacher supply store would have a lot of stuff to teach this - many fun/game type options.