Topic: Diving + Good hotel on Railay for couple with 2 children

Gents and Ladies,

We are travelling to Krabi in end Sept for 5 days - and wanted help on three specific things:

1. Whats the best hotel on Railay that is child friendly, clean & comfortable and doesn't cost the earth?
2. Any recommendations on Dive operators who are highly experienced and know the best dive sites? I want to do an advanced open water dive course.
3. What are the activities that MUST be done while at Railay?

Any responses would be greatly welcome!