I believe WVGA = 720p, but you might want toGoogle it to confirm.
You will get about 4mb per hour at 720x30fps or 8mb per hour at 720x60fps. Balance that against battery life and video card size. A standard GoPro battery will last just under 2h, so you can run 720p x 60fps and fill a 16gb card in the time it takes to deplete your battery.
Standard TV and YouTube frame rate is 30fps. If you're not editing your video, stick to 30fps to keep your file sizes smaller. If you edit and want to show some slow-mo, shoot in 60fps and edit to 50% speed to slow things down. You can go slower, but it will be jumpy.
The GoPro Hero2 will shoot x120fps and the Hero3 at 240fps at that resolution so one could even go 1/4 speed or 1/8 speed, respectively.