Me too. Almost always inside of front legs and usually outside of hind.
Unless he moves in a peculiar way putting abnormal strain on himself I would suspect he has been injured, maybe kicked there. It looks massive, I would get it x rayed if it is growing, and I'm not one to get the vet...
I always remember being at my friends who had two large ginger cats. One constantly hunted rabbits and left the ears and tails in the porch. I spotted him one day resting on the clothes in the laundry basket. He woke up, leaned over the side and accurately threw up half digested rabbit directly...
I wouldn't do it. 6 miles is our "round the block" hack.
It might be an option to split it and have a walk and trot only ride so it was suitable for lead rein or youngsters without the worry of someone flying past, then a ride for others.
Nearly always. I tend to look round breeders and buy youngsters.
Current pony is a bit different in that I was after a new Icelandic but didn't want to spend much and I was taken by his cute foal picture on Facebook.
If he's capable of jumping the course and doing a short show just go for it. You've nothing to lose and if he can jump clear in a sensible manner will likely be better than many.