We will have a rental car but will it be faster to use bus transportation back and forth or our rental car to TTC and take a ferry or monorail over. We have a 9:05 CRT breakfast that day and are flying out at 2:30 that afternoon
Normally I'd suggest taking the Disney bus to the MK so you don't have to deal with the whole tram to monorail/ferry part of the journey. However, since you're leaving that day (presumably directly from the MK) it would probably be best to drive there.
Another vote for leaving directly from the MK via car. If you want to take the bus, I'd allow at least 45-60 minutes to get from MK back to Kidani. It'll save you some time and give you a bit more control over how/when you get to MCO.