TenGrainBread 

Both brake squeal and brake power are subject to many different factors, some of which are not very obvious.

For the squeal, check these things:
-Are the pads contaminated or dirty? Clean and file the surface of the pads. Check for bits of rim stuck in the pads.
-Are the brake tracks contaminated or dirty? Clean the rims. If that doesn't work, take a scotchbrite or steel wool to shine the brake track up. Rinse the brake track with isopropyl, not a cleaner that leaves a residue. Same for the pads.
-Are the brake pads toed in? This can sometimes eliminate squeal.
-I have also seen adjusting the angle of attack of the pads reduce squeal.

As to power...what brakes do you have? Are the brake pads close to the brake arms or farther away? Are the two arms evenly spaced from the rim? Adjusting this will change the leverage the arms have on the rim and might reduce flex in the pad holders. Same with adjusted straddle cable height.

Re: V brakes: the pull ratio is different than cantilevers. Cantilevers use "short pull" or "road" levers whereas most V brakes use "long pull" or "mountain" levers. So you would need to change levers, unless you got a special V brake that is short pull ("Mini V brakes", like the one from Paul Components. V brakes are subject to squeal just as much as cantilevers. They are usually somewhat easier to set up due to not needing a straddle cable and hanger. They are more powerful than most cantilevers, meaning they will feel more grabby and a little less modular, but have greater stopping power.

My advice would be to take the bike to a trusted professional mechanic and see if they can get them working nicely. If so, simply ask them what they did and you will have your answer.