1. I have as many books as you.

Question

2. I have as much money as you.
3. I have more books than you.
4. I have more money than you.
[Are they all grammatical?]

5. I have as few books as you.
6. I have as little money as you.
7. I have less books than you.
8. I have less money than you.
[What about these sentences? Can we use them?]

Answer 1

1 - 6 are all fine.

7 and 8 would be fine if you use "fewer" instead of "less" -- "book" is a count-noun, so "less" is incorrect.
http://grammar.ccc.commnet.edu/grammar/noncount.htm