yes, for mining scrypt better to look at something called terminator, or you can simply build your six gpu rig and try to mine any new altcoin
something soft like 6 x 750ti will cut it
a setup like that gets close to ~1000 dollars, might be better to buy a scrypt asic at that point.
maybe, but the big difference is that with gpu you're not limited to one algo, and you can mine any coin out there, plus gpu can always be resold easily