I'm local. Will respond in a bit
July will be monsoon season. We've had a bit of rain as early as now but expecting the annual typhoons to come later.
Whale sharks: Strongly advise to avoid the whale shark watching in Oslob, Cebu because they engage in unsustainable practices. Donsol is better in that respect.
Film developing: local fujifilm outlet in Manila accepts color developing. I can send you addresses via pm. Black and white developing takes a while (3 to 5 days) and is serviced by independent labs. There's been a resurgence locally brought about by the young crowd.
For scuba diving, there's a ton of sites just a couple hours drive from Manila. Anilao, Batangas comes to mind.