On this page, it says that "plus de" is an adverb of quantity.
That page links to this page which tells me more information about "plus de".
There is a section called "Comparing Nouns". Here are some examples it gives:
J'ai plus d'idées que toi. (Comparing a noun between two subjects)
I have more ideas than you [have ideas].Il y a moins de pommes que d'oranges. (Comparing two nouns that are objects)
There are fewer apples than oranges.
Question 1:
When "plus de" is used to compare nouns, as in the examples above, is "plus de" still considered to be an adverb of quantity? I had thought it would instead be considered an adjective, because adjectives modify nouns?
Question 2:
If I want to say "more [noun]", in a way that does not compare, as in:
I am a poor student. I want more money.
Can I use "plus de"? The page I linked to doesn't seem to suggest that I can.