Since you're aimed at the Guns Akimbo line of firearm awesomeness, keep in mind enchanting multiple weapons gets expensive really fast, plus the problems that already exist with both ranged combat and two-weapon fighting (a.k.a. total feat sink). While I enjoy the imagery, it takes a while to setup, so you'll be piddling away for awhile before you can turn yourself into a badass.
Also, Rapid Shot only gives one extra attack, not one per weapon. Annoying, I know, which is why I explicitly point out that bit out in my Crossbow Slinger PrC, should you want to see how I got crossbows up to Guns Akimbo.
Happy gunslinging! :D