No, the word avarice usually has a negative inference. Avarice is described as an insatiable greed for riches; inordinate, miserly desire to gain and hoard wealth; it is also one of the 'seven deadly sins'.
if you mean like rash behavior, its usually negative because it means you jump right into something without thinking. most of the time that's not a good thing.
Well, it depends what kind of words you want to make positive, for example if you use the word smell as an odor type (negative) then a positive way to say it is aroma, scent, or essence.
Another way...
A base word is a word that has a prefix or suffix added to it (e.g fix, refix, fixed.) Fix would be the base word. A root word is a word that another word comes out of. "path" is the root word that...