Teeth checked and done, dewormed and groceries.....LOTS of groceries.
When he's in proper weight you can go and try saddles. I have a square skirt SQHB 16" Big Horn Flex tree saddle for my 14.2 ultra short backed Arabian. It has 25" skirts and it fits fine. Couldn't be half an inch longer, tho
As for Barrelracing, depends....of course Arabians can do that. If my horse was high strung to begin with I'd think twice tho.
With this one I'd ask the seller some serious questions as to why this poor guy is so thin....