I don't see a problem with bridging an amp. So if you already have that amp I would use it. Provided it IS bridgable and the subwoofers are at a stable impedance for the amp. For instance, most amps are not stable if bridged with a 4ohm load and very very few are stable at 2ohms bridged. So make sure it's capable.
You haven't chosen your subwoofer yet? Most subs come with an amplifier built in. If you're going to buy a passive subwoofer then you'll need your amp. But that seems unlikely.
Hooking it up is easy. Just use an RCA splitter.