Vaquero's are a great plinkin', short range hunting gun. Once you get use to the sights, you'll do fine at ranges the game you mentioned is normally taken at.
I would't get toooooo caught up in trying to make a fire-breather out of it (unless you just want too, which is alright too!).
A REAL original .45 Colt type load, like a 250gr SWC at around 900-1000fps out of your barrel, will easily shoot straight through any deer you'll ever see, and leave a large wound channel. Plus it will be very shootable to boot. So loaded, it is by NO means a pipsqueak.
FPE is very misleading.