Jaguars price varies alot, I bought mine last year for $1000 but they come as cheap as $150, however I'm in Canada so prices will be different. Again for good breeders I won't be alot of help, but there are plenty depending on what you want(so much to choose from, not as simple as just asking for a jaguar lol)

The disability is much like the spider ball pythons disability, occasinally spins, occasionally can't hold its head up straight, and sometimes even goes completely upside down. Generally though, the neurological disorder is quite minor, again like spider ball pythons. Like said above really nothing to worry about.

The Jaguar is a codominate gene originally found in coastals, but has been bred into the other carpet subspecies, as well as bredli pythons and green tree pythons. But yes the jaguar gene is coastal and there are pure coastal jag's available. Would want to buy from a reputable breeder to be sure.

I'm sure a pure coastal jaguar has the same growth potential as a normal coastal, when you start getting into integrades I'm sure they can still grow up to 11 feet I mean who really knows. The point is, be ready for it lol, if it does get that big can you provide an 8x2 or are you stuck with a 4x2. Maybe get a male then, as the likely hood is much smaller(never seen a male coastal over 10' myself, I'm sure they're out there though)

Good luck, carpets pythons are amazing snakes to own. ~Caylan.s.~