Quote - Is there anyway to prevent people from adding your image to there favorites?

No.

Quote - Or block people from downloading your images?

No (unless you don't post them at all).

Quote - I mean we all know that the Art Charts are a farce and should be called poularity charts as placement has little to do with art.

Nothing wrong with popularity, just ignore them if they don't live up to your ideals or play them for all they're worth to see if you can break them (c.f. Pink Pony).