Canti brakes are usually easy to set, but sometimes are a pain. When they are a pain, I find it helps to clamp (or third hand, if you have one) the pads against the rims, and then pull the cable tight, and then tighten the bolt. Its easier to do if you are not fighting the springs in the canti arms at the same time you are tightening. Barrel adjusters are very helpful to dial them in also.

I think you did a great job finding the bike and getting it running. I also consider myself to be not overly mechanical, but bikes are so simple that they are very satisfying to work on. There are not many problems that I can't solve just by thinking through.

jim