Chikungunya has made it here, and has a confirmed case that doesn't originate from Caribbean travel. A bribe in the right place to let someone get on an international flight, and we've got serious problems. The big thing keeping Ebola from being truly terrifying is that it's spread by fluids, not through the air. That, and it's acquired from African animals. It would be quite difficult for it to obtain a foothold here in the US, and then migrate to a wild animal population repository. It's a bit different when your society doesn't require the eating of wild animals.
It does spread from sweat though, right, as that's a fluid? That, and our awful open southern border, is why I'm more concerned.
I believe so, but again, you've got to connect the dots. How much travel is going to originate in African areas, head to Mexico via some path, and then trickle across the southern border? Especially for people that are consuming bush meat or those that come in close proximity to said people?