There is no set order of stops, up to the driver dependent on traffic and how many people are going to each resort. Sometimes it's just two resorts loaded onto a bus, never seen more than four. It really depends on the flights coming in and what resorts those people are booked at.
Been to CSR 8 or 10 trips (lost count!), it's our favorite resort. We've had the POP, CSR, and AKL/AKV on our bus, often it's just POP and CSR. Sometimes CSR is first, but we've most often had POP first, then CSR, then AKL/AKV. So most times CSR will be the second stop, though it's not a set schedule.
The 90 minutes is from when you step off your plane to checking in at the CSR front desk. Includes getting to the ME area, checking in at the ME podium, waiting for your bus, making a bathroom stop at the airport after being on a plane for a few hours, etc. I don't think a cab would save much time, since then you'd have to go to baggage claim and get your own luggage too. If you stop at POP it's no more than 10 minutes, often less. ME makes their stops only at resorts in the same area, never too far away from yours.
As far as coming home, the three hours before your flight time gives ME time for traffic tie ups and dropping off at different MCO terminals, as well as picking up at other resorts. Again, we've often had just one other resort stop after CSR on the return, sometimes we are the last stop so head right to the airport. With MCO security screenings sometimes backing up, and occassional traffic tieups, it would be cutting it close to take a taxi even two hours ahead. The extra bus stop doesn't take much time.
Besides, a taxi will cost you at least $50-$60 (?) one way. Mears shuttle is about $19 one way person, but might make multiple stops too. WDW is not that close to the airport. The video on the ME bus ride is cute, the extra time involved for ME isn't too much, and ya can't beat free. (Yes, I know the cost is really part of the room rate!)
. I'm thinking maybe a cab would be better.
