I can't answer any of your questions (how many holes, how does it sound) but I know that almost any chromatic is pretty pricey (at least $50-60). If you can get a reasonably priced one, it may be worth getting, just to see if you like it enough to upgrade.

Little Walter played blues on a chromatic, generally in third position, which makes good minor chords. Portland Oregon's Paul DeLay is (in my humble opinion) the current master of blues chromatic harmonica.