Question

e.g. Do you want to know more about him?

(What is the part of speech of 'more'? Is 'more' a noun or an adverb?

1. Do you want to know know much about him?

2. Do you want to know a lot about him?

3. Do you want to know a lot of things about him?

4. Do you want to know many about him?

(Are the four sentences grammatical?)

Answer 1

In that sentence, "more" is a noun.

All of those sentences are grammatical except # 4.