strarting over is a good idea

Exactly how many is some third party applications? The cardinal rule for installing any application is to install one at a time then use your computer extensively be insure compatibility. Installing more than one application simultaneously (except Apple products) is just asking for trouble.
By erasing your had disc and starting over, you did the right thing.
I cant explain the F1 - F5 key problem since I don't have that problem.
Ive never owned anything but Macs. Theyre not perfect but OSX is the most stable of the operating systems Ive used.
Since it sounds like most of your problems are third party software problems, dont blame Apple. Give it time.