RE: wut kind of bow
At the tournament I just came back from, the guys that brought in 160 fish were using 30lb bows. The lighter poundage kept the arrows from jamming into the roots and mud so they could retrieve fish and arrows faster.
I was using only a 45lb bow and sometimes I had to really fight to get my arrow back from the bottom of the lake. One time it took me 15 minutes to get my arrow back. (I'm using a 23.00 Muzzy Carbon arrow... so I really didn't want to leave it)
Your old bow sounds like an ideal weight for bowfishing. 55lbs is really overkill.
Good luck!