I will be on Ambergris April 5-11, with my family. Couldn't find definitive answers on the web to these questions:
1. Sim card purchase in the airport or via hot guide prior to arrival?
Belize hot guide
Can one purchase a sim in San Pedro?

2. Our visit is over the Easter Sunday weekend.
2a. Will stores, restaurants, shops, fishing/snorkeling excursions be open/available?
2b. Special events on Easter?
I believe there is a "Cross" Walk/Parade on the afternoon of Good Friday.

3. Is there market for local goods, fresh fruits, art?