Soundcraftsmen pa5001 questions

I have a Soundcraftsmen pa5001 that i am thinking of using as a makeshift bass guitar amp. I have a bass guitar preamp as well as a 15" cabinet.. Basically like a subwoofer system, sort of.. My questions are:
1) Will it cause any damage to the amp to use only 1 of its two stereo channels and have the 2nd one not hooked up to anything..
2) I read this amp is bridgeable. Could i bridge the Left/Right channels to run the preamp thru both and both out to a single 15" cabinet. The back of the amp simply has a 1/4" input for A/B and 2 sets of speaker outputs for each channel. How would it be wired to bridge???

I know many here will likely think this is a waste of a great amp and i should sell it to someone who wants it for a stereo amp and buy myself a proper bass amp! Just trying to make use of what i have here and i think it would do the job fine.
Update. I wired this up today and wow it sounds great! A friend suggested i could get a 2nd 15" cabinet and Y the signal from the preamp so it goes into both channels and then run it out the 2 cabs. No real need for it though as its plenty powerful as it is.