My wife has similar issues, many of which went away when she upgraded her bike to one with Shimano 105 brakes. More recently, she had a complete bike fit, which included new, smaller bars and having the brake levers shimmed so that they are nearer the bars to start with. It's now even better, but she still isn't confident on long descents as she still finds it quite difficult to apply force to the levers.
The next step is to upgrade the cables (inner and outer) to reduce any friction, but that is a bar tape off job, so I'll put it off for now...
So, as someone has already said, make sure that the system you have is in good condition, replace brake blocks if necessary (actually on my first bike, I found that swapping for good quality blocks was a very worthwhile upgrade, so maybe do it anyway), check cables, etc. Shims will help, but if extra levers on the "tops" will help to give you confidence and encourage you to get out and ride, then do it!