Nice choice, BB! Welcome to the Brickyard club and 350z-tech.
Those wheels look great. Did it come with them or did you put them on after you purchased?
As for juicing up the Z, based on my experience and of those I know...
1 - Top NA mods you should be looking at... #1. a good set of headers (for low end torque). I, of course, recommend the Crawford headers... a bit more expensive, but the best proven gains on the market. #2. a lightweight flywheel... maybe the best bang for the buck out there. This will make your car feel so much more responsive.
2 - If you have the cash, best bet is to join the FI club. Go with a supercharger for lower entry cost, less headache, and easier tuning. Go with a TT if you want to shoot for bigger power numbers.
3 - do NOT get the TechnoSquare reflash unless you are local to someone who can dial it in for you or you have time to mail your ECU back and forth several times. Definitely don't do it until you get all your other mods on. That way you only have to do it once.