Sounds like a brake upgrade is definitely in order!
Depending where you get the brakes from (check with the store), they should come with 4-bolt mounts if it's from anywhere trials-related. It's worth upgrading to a 4-finger lever blade straight away, and depending on your frame, getting at least a 2-bolt booster too. Most riders grind their rims these days, especially now winter is coming, so that might be worth considering. However a good level of braking performance can be had on a smooth rim.
The pads that come with them will last ages, but work poop! Those are the main thing that you should get whilst upgrading, from what you've said, it'd be worth getting some pads that are gonna work on wet and dry, on smooth or ground rims
As for whether the 11's or 33's are better.. the 33's seem to be placed higher in the model range, but I think the general consensus is that the HS11's are just as good in reality.