Considering dark rides have used wind to simulate moving faster then they really are, that's a non-issue.
As for the idea of a interactive family coaster, that's not feasible for MK in any way, shape or form. While there's a couple coasters with legit interactive/shooting moments, all of them come to a full-stop for those segments. That alone doesn't work for MK which has you shooting items aplenty while moving. An if it would be moving, it would be around the same speed of a darkride since any faster and there's no way in heck you'd be able to aim/hit anything. MK is seamless, frantic chaos. It doesn't slow down to fire items, so it's better using a darkride to have a nice control on everything going crazy for the whole ride. A coaster would be too much start-stop-start with those elements.
As for opening paths and secrets, those only come into play when you're racing in the actual games. They're not high on the priority list when it comes to making a ride based off MK.