Of course the shape matters, everything matters. But does it make a noticable difference? chance is pretty slim, considering two bodies of the same wood and mass, unless the shape of one of them is really out there (like a 1,5m long stick) the difference would hardly be noticable.
Biggest trap when planning a guitar is reading into too much bullshit on the internet. Just because someone figure out how to post their thoughts on the web, doesn't give them credibility unless they can back their theories up. In most cases, someone just comes up with something that seems logical to them, posts it on the web, 100 people who don't know better regurgitate the "information" somewhere else and after a while it's suddenly a fact.
I'd say worry about the stuff that will have a major influense on sound, don't bother about the rest of the voodoo. IMO it's impossible to predict exactly how a guitar is gonna sound anyway, so just build a guitar with components that are proven to work and get some experience...after a while you can start experimenting with way-out-there theories.. (even if you hear someone who claims they've experimented and come up with amazing results, the truth is that the amount of data collected is most likely waay less than what's needed to actually prove a theory)