I was going to guess that the fence was about 3ft, possibly 2'9...figure it's probably a 5ft standard.
You could easily do lower level events or jumper classes with him, so long as he's brave, has stamina for jumping, & doesn't have refusal issues. Colour is NOT an issue in the jumper ring, & is very rarely an issue in eventing (with rare exception of bad dressage judges at unrecognised shows).
Jumping is hard on a horse's joints, especially when they are started at a young age, so yes, he could have joint problems later on down the line. However, just don't over do it & take good care of him, & he theoretically should be fine.