more than one Impedance on 4ch amp

first of all, this site is truely amazing.  i've learned so much and gotten so many ideas from you guys.  this will be my first post.  thanks!

alright, i've installed a bunch of systems in my day, for myself and for friends, but ALL have been simple one amplifier channel per speaker.  i honestly never even bothered learning about impedance but i want to change that now. 

i have a KDC-X990 hu and an old but never been used RF 301x  4-channel amp.  i'm planning on powering a set of infinity KAPPA 52.7i  (2 ohm impedance and 55w RMS) and a set of infinity PERFECT 5.1 components (4 ohm impedance and 100w RMS)  that i've also already bought but not installed.  is that a problem running two of the amps channels at 2 ohms and the other two at 4 ohms?  i know it's stable at both 2 and 4 ohms but i don't know if you had to run all 4 channels at the same impedance or if you could mix it up. and can i expect the advertised 40x X 4 @ 4 ohms RMS from those 2 channels and 72w X 4 @ 2 ohms RMS from the other 2 channels?  i wish i could reverse that and send more power to the components cuz then the wattage would be perfect to both sets, is there a way?

as for the low end, i'm thinking of getting another fosgate 301x for asthetics (twin amps) and pushing 2 infinity perfect 10 subs.  i know that's not alot of power but i'd really like to keep the amps the same model or brand at least.  i'll plan on eventually replacing both amps at the same time in the future.  but for now just bridging 4 channels into 2 which will give me an advertised 150w by 2 @ 4 ohms bridged rm.  i've heard RF is notorious for under advertising their power.  so any thoughts on all that would be appreciated too.  thanks again guys