hmmm.. the shop i got my OW from required mask,fins,snorkel, and weights (figured on 10%) --didn't have to buy any of it from them though.. rental of everything else was included (including the boat trips)
not a bad shop, decent instructor - but didn't offer any help with diving afterwards (like a dive club, or recommendations towards one of the many down here) they sell mostly aqualung & scubapro.
as a rule --- ANY SALESMAN is going to recommend whatever they can make the most money on... doesn't matter what they are selling...
unless you have money to burn -- rent until you are ready to buy and make your decision based on your budget, what kind of diving you're doing, and how often!!
jacket, back-inflate, BP/W, various brands -- try rental from different shops until you find one you like....
everyone has their own preference on regulators & computers -- i like atomic for my reg and all of the atomic line breathe exactly the same-- it's just the different materials...
you're in florida --- the only consideration you will have about warm vs cold is how thick your wetsuit is going to be for the season.
don't worry about spearing until you're certified and comfortable underwater -- spearing adds big taskloading and can affect your buoyancy depending on what gets speared.
i bought a back-inflate and will eventually go to backplate & wing myself... and i have splits and hollis f1 batfins
the only opinion i'll give on a computer when you eventually buy it -- yes make sure nitrox compat. other than that it's whatever you want.
all regs are nitrox compat out of the box up to 40% and say it in the manual.
don't be afraid to wait to buy.... and it's possible to find good deals on used equipment too... either on here or craigslist locally. also many dive shops after a while retire their rental gear that's in good shape for great prices. ask around at various shops....