A few is usually more than two (two often being referred to as "a couple of"), and less than "several". Few emphasises smallness of number, while a few emphasises some:
He's a dull man with few ideas vs. He's a clever man with a few ideas.
However, the following excerpt is contradictory
A couple of is different from a few in that it does not imply that the relevant amount is relatively small. One might say admiringly of an exceptional center fielder that he can throw the ball a couple of hundred feet, but not, except ironically, a few hundred feet, which would suggest that such a throw was unremarkable.
Similarly contradictory is the idiom not a few, which actually means "not few"
FEW (determiner) 8. not a few (informal) ⇒ quite a few, several.
I hope somebody can help me clarify this whole issue: why does he can throw the ball a few hundred feet suggest that such a throw was unremarkable?
I know "He can throw it few hundred feet" is not grammatical, unlike "He can throw it few feet (off/away/etc.)"
Also, you need a if it's preceded by only, as in I ate only a few apples and a little soup.