If you search and read back through, you will discover this changes, a lot.
We've stayed at CBR twice, once in January, once in February. BOTH times, it depended on the park. Going to and from Magic Kingdom, buses enter over by Riviera, pick up at Martinique, main, Barbados, Trinidad, Jamaica, then Aruba. They drop off in the same order.
Going to and from AK, they entered at the main gate which means they started at Jamaica, Aruba, circled over to Martinique, main, Barbados, and then Trinidad
We have never had the buses split the resort, but I have read that happens at super busy times. (christmas, new years, spring break).
I'm sure others will have different experiences. We've been known to get off at the main building when returning from MK, to grab a drink and then walk back to our room.
Hope that helps.