Personally, I wouldn't touch this guy with a ten foot pole. He's extremely fidgety, not at all happy in what he's doing, looks very "pully", going around with his mouth open. Can't see the bit but I'm willing to bet it's not just a light snaffle. He's very stiff and short strided in the back, maybe the beginning of arthritis? He's pretty, but that's about it. From the ad, we know he was injured badly enough to need surgery, and that they recommend him for an experienced rider, which more than likely means he's pretty strong, or has some issues. Not likely a good choice for a first horse, especially considering your particular physical concerns. But that's just my take on it.
"Keep a leg on each side and your mind in the middle"