Going to Disney you may or may not have to clear or reclear customs in Orlando.
If you do have to clear or reclear customs in Orlando, you ...
1. Get your luggage from the right side(?) conveyor belt at the customs station.
2. Clear customs.
3. Choice of:
3A. Take the luggage with you, all the way to the Magical Express bus.
3A1 Sometimes the agent denies you this choice.
3B. Put the luggage on the left(?) conveyor belt, then
3B1 Yellow tagged luggage will be delivered to your resort room.
3B2 Non-yellow tagged luggage will be delivered to the main carousels
3B2a You may claim the non-yellow tagged luggage and go to the ME bus.
3B2b You may go directly to the ME area and they will make resort delivery arrangements
If you do not have to stop at customs in Orlando, then the airline starts the process sight unseen and you start by choosing 3B2a or 3B2b.
Going home, all international travelers must clear or preclear customs in Orlando and therefore must manage their luggage that day and bring it to the ME bus.
>>> How many British ...
Guests are commingled on the ME buses regardless of which flight they got off of (or how they got to Orlando Int'l Airport).
>>> Will the coach take ...
Most luggage is put under the passenger cabin, for which you tip the driver when you get to Disney. Buses have small racks above the seats, no sturdy bins.
Disney hints:
http://members.aol.com/ajaynejr/disney.htm