I would have to say judging by your pic you don't look bad, but you do look a little older than you are. Maybe its your dress sense? I dunno, but I think you do need a little sprucing up! Anyways, here's my two cents:
Not much help there (as a guy), but looks like you'll probably have to find some good stuff for support. Probably something like Bla Bla Bra or Triumph? (I heard these are OK for big-busted ladies).
I believe you should find something comfortable that you feel really comfortable with and don't mind wearing - that confidence would make you look 'sexy' to your guy. Doesn't always have to be a 'plunging neckline' type dress/top, but it would help in most cases ie. V shape neckline tops/U-shaped vests and slightly tight fitting than the one in your pic. Something like a floral dress or tanktop/denim skirt/jeans would look nice on you I think.
In Asia (where I live) there's a wide range of shoes available and I think the wicker wedge/platform thing as well as the half-leather boot is getting quite popular amongst the girls at the moment. That coupled with hotpants or miniskirts or trousers with stilettos might look good for you.
I think for you, you're probably better off with dying your hair something like a brunette red/blonde and keeping it fairly short and straight; or cut to shoulder-length medium. Most guys I know hate frizzly hair (which you have), so I'd think it would be a good idea to change it!
Play to what your man likes. I'm sure you know some of his favorite outfits of yours. Put together something totally new, but that has things you know he will like. I love a pleated skit for example. Just find enough things that go together.. and make it a color you know he enjoys seeing on you. My personal thought is red.. its very hard for a girl to look bad in a hot red outfit.
depends on the guy. For me I like cutesy/innocent looking girls. I feel that so many girls think that dressing slutty makes them look hot, but in reality this really just turns on ghetto dudes.
I still have a fantasy of banging a cute girl in her early 20s in schoolgirl uniform. That's me, but I know innocence is sexier than you think.