Definite article before "most", "several", "some" and "few"

Hi. Please help. Could we put definite article "the" before the words "most," "several," "some" and "few" in sentences? Is specificity of the object or objects mentioned required for us to put the definite article before the forementioned words like "most"? And if that is so, does that mean we do not put the definite article "the" before those words when used in sentences that mean to say something generally? I hope I wrote my questions correctly to reflect what I wanted to say, but I am not sure. As to no. 4, I think putting the definite article "the" before "some" looks incorrect, but I can't explain why. Anyway, your help would be appreciated. Thank you in advance.

eg,
1. (The?) Most of them were literate.
2. The most of them who were there were literate.
3. This applies to (the?) most of them.
4. The most/several/some/few people who were here yesterday were friendly.