If you are going for 6 months:
1) you are very lucky!
2) You don't really need to figure out
now which dive shop you want to train with, because you will have plenty of time to figure out which dive shop you like when you are there.
Since you have so much time, you will have time to check out all the major dive destinations in the Philippines. In no particular order, check out Puerto Galera, Malapascua, Southern Leyte, Moalboal, Dumaguete, and Bohol. If you like shipwrecks, check out Coron too. Maybe others will chime in with their favourites.
You have enough time to spend 3-4 weeks at each place, which is plenty of time to get the lay of the land and figure out which dive shops you like and want to train with. There are plenty of good operations to choose from.
As for getting paid to dive, most westerners will find the money quite small, which is why the locals end up doing most of there dive-mastering. Most westerners will have trouble competing with the locals who dive master as their full-time profession for many years. Since the Philippines is a poor country, locals can survive on the pay of a dive master. Westerners would have trouble surviving on the pay of a dive master unless they are willing to live very frugally.
Instructing is a bit different, but you are still a long way off from that. Start with your AOW, then rescue, then maybe you can think about doing your Dive-master after a few hundred dives.
Have fun!