He is already looking better
. His hooves are a little long, but not bad at all... the typical thoroughbred feet. I wouldn't put shoes on, as long as this is the ground he is living on. It will be better if he can grow nice feet( with the help of good nutrition) before they get restricted with metal shoes.
I also agree to wait with exercise. Maybe take him for a walk with halter and lead rope, around the premises.
This is definitely wheat straw. If you can find some clover hay, to mix with the straw, that would give more calories and, more important, balance the calcium: phosphorus ratio. it should be 2:1, I bet right now it's 1:1, or worse.
Also, make sure he has always something to eat (roughage)in front of him. This is the most important thing, for weight, for energy, for happiness.
The supplement is, as far as I can see, vitamin E and selenium, needed for muscles. Good to know that you have a vet pharmacy there, if you cannot find any clover hay, you can get a calcium supplement there, I'm sure.