Brakes
 

I have a bad back and my touring bike has flat bars. In your opinion would I be better off with cantilever or V brakes? Thanks in advance.

It's personal preference. V-brakes have more stopping power and some people claim they are easier to adjust. OTOH, cantis can be adjusted to lock up to a skid and I find them easier to adjust and just less of a hassle.

I think Vs can be a hassle with fenders? Something anyway. I have Vs on my recumbent touring bike, and no problems with them, it has fenders and racks, but the racks aren't near the brakes, on my touring bike, I have cantis, pauls on the front, or will if they ever come in, and I have pedersens on the back, those buckaroos will crush your rims if you need to.

Since you have flat bars and also levers that go with them or will be getting levers that go with them, V-brakes are the ticket. To get cantis to break anywhere near as well as V-brakes you have to set the pads very close to the rims and the yoke nearly horizontal, even with that the control is still not as good as V's. With V's there is a small screw on each side that allows you to adjust the distance to the rim independent of the other side. Canti's have an inherent flaw in that the harder you apply the brakes the less leverage you have because the yoke cable angle increases as you apply the breaks, V's do not have this problem. Add a set of kool-stop pads and you will be set.