Sorry to hear you are having some many problems. I love my 60C, but maybe thats because I haven't used anything else..
To delete all of the waypoints, go to the Trip Computer screen (the one with the odometer, speed, and moving times) and press the Menu key. choose the Reset option. You will see the option to clear out all of the waypoints.
I use GSAK with mine, and I agree, I really really wish I had more information stored in the unit rather than having to print out the information.
I will be honest, I REALLY like my unit, but again I haven't used anything else. Hope you have better luck!