^ But he said freehub, not freewheel. My experience with freehubs is pretty limited, so I won't venture to answer that question.

As to question #2, re brakes, it could be any number of reasons from old brake pads, to set up of the centerpulls, bad cables, dirty/greasy rims, etc. I haven't used those levers in combination with centerpulls. Assuming that's not the issue, my first instinct with poor braking is to check brake pads and rim surface. Are the pads new? If they are old, sometimes you can file the surface to expose softer rubber, but I find that once a pad gets too hard it's better to simply replace with new pads. Have you tried cleaning the rim surface? Do your centerpulls have the ability to adjust the straddle cable length or is it a fixed length straddle? If the former, I'd play around with straddle cable length and adjustments of the rim-to-pad distance to see if that makes any difference. I had some Weinmann centerpulls that gave poor performance when adjusted very close to the rims. How new/used are the cables? The rim width can play a factor too. Maybe a photo of your setup as is?