the amp clips when its driven past its specs. notice on the spec sheet its stated '91rms @ <1%THD' - this is the distortion spec. they didnt get that value by maxing the gains. any amp will distort if you push it too hard.
yes, the amp is perfect for those speakers. sounds pretty decent.
and yes, you can use that amp on the subs. i used a 1500wrms amp to power 2 subs rated at 350 apiece
havent blown them up yet