What is the role of 'a lot' and 'much' in my sentences?

Can we use adverbs before pronouns?

As we know adverbs are normally used to modify 'other adverbs' , 'verbs', and 'adjectives'. e.g (I'm feeling a lot better today.)

I consider 'a lot' and 'much' as adverbs and 'more' as pronoun in the following. Is my analysis OK?

I earn a lot more than my sister does.

I have a lot more in common with my friends than my family.

I can't stand much more of this.

I eat a lot less than I used to.

You shouldn't consider a lot and much as Adverbs. They're actually a different part of speech -- Quantifier -- which wasn't discovered until after Donatus specified the Eight Parts of Speech, around the Fourth Century. So you're not playing with a full deck.

Quantifiers are a type of Determiner, like articles; they indicate amounts and have very special syntax. Treating them like adverbs just makes more problems. Like the presuppositions underlying this question.

In comments BillJ wrote:

“A lot” is a noun phrase and “more” can be either a determinative, as here, or an adverb. In your examples “a lot more” is an NP in which the determinative “more” is functioning as a “fused determiner-head”, i.e. the functions of determiner and head are fused together into the single word “more” (cf. “a lot more money”). The same kind of analysis applies to “a lot less”.

It's crucial to grasp the difference between 'category' (noun, verb, adjective etc.) and function (subject, object, determiner, modifier etc.). In "I like him a lot", "a lot" is an NP (note that it has the article "the") functioning as an adjunct of degree. And in "I earn a lot more than ...", it's still an NP but this time its function is that of pre-head modifier to the fused determiner-head “more". There is nothing new in any of the terms I have used.