My thoughts: 1) yes, you could see it from the cruise terminal area. Not necessarily totally from the ground, however, since it's a distance away, but you'd see it once it got high enough in the air.
2) I don't know that I'd risk trying to watch the launch at KSC and then hightail it to the port, as launches are quite likely to be delayed or even cancelled. And they don't tell you about it until you figure out the rocket didn't launch (in our experience).
3) Even if it did go off on time, the time it would take you to get from the viewing area at KSC to where your car would be parked, and make it to the rental car place then to the terminal is pretty tight.
Thanks! If we get to see it, it will be a real bonus. Worth the effort of flying 12 time zones.