To answer your first question: What style guitar will sell the best? (Jackson Soloist vs. LP)?
This really depends on what kind of music you play and how picky you are about staying in tune etc... A Les paul styled guitar is grate for blues and most of the rock on the radio because of the tone (if set up right with the right pickups etc) On the other hand, if shred is really your thing you might prefer an note churning shred machine. to be honest most if it is really down to looks as both styles of guiar can be used for anything if you are willing to work at it.
A good floyd rose with a locking nut is definately worth the price over a vintage tremolo. The guitar will actually stay in tune for most of the strings life (usually changing them at least one a season if not sooner - ie every gig or so) if you tune it properly to begin with. The slight downside is the the tone stealing capability of the tremolo, which can be easily fixed with a decent Seymour Duncan or Dimarzio pickup or two.
Chrome tends to sell better on vintage looking instruments whereas black works best for shredders. really, though, the quality of the parts on the instrument will be te selling point.
Also, don't be dilluded into thinking that if something has a Gibson or Fender badge on it it must be good. Those companies have been making basically the same instruments for years and while they do have a solid workhorse instrument for each brand, there have been advancements in technology which enable the same instruments to be made for much less than their vintage counterparts. That said, there is nothing wrong with the guuitars that these companies make, I just prefer guitars that have a great tone AND will be in tune when I pick them up.