I think you've had most of the answers you require, but hidden in a lot of dross. To summarise:-

(1) You did post in the right place - the CC forum is nowadays a part of the AC one.
(2) Two operators on CC that are highly regarded are Belize Diving Services and Frenchies.
(3) If you like the resort course you can extend it to the "PADI Scuba Diver" certification level, which takes an additional 1 1/2 days and about doubles the cost. But it does give you a dive card that's good for life.
(4) The resort course is undeniably worth the cost and it is a very good intro to diving.
(5) You can do the full PADI Open Water certification course in just one more day.
(6) Depending how long you have before you come, you can arrange to do much of the work at home before you get here, minimising your learning time when on holiday.

Any help?