I recorded a video with my GoPro, only to find out the horizon is not exactly horizontal, it is off about 5 degrees, can Fast Cut correct this? Or is it like other software that only does 90 degrees at a time?
AFAICS Fastcut only allow 90 degree rotation - to rotate an object you need a more advanced program such as Movie Edit Pro which allows rotation as fine as 0.01 degrees.
If you do decide to get Movie Edit Pro get the Plus or Premium version.