Licensing and hiring
You do not need to convert your FAA certificate. I'm living proof as I fly in the PI and I'm doing so with what is called a validation. My FAA certificate is what I use but several countries are accepted. I do need to keep my FAA valid and that means my medical and also a PC sim check is required per regulations.
Cebu Pacific is advertising again for pilots and I'd recommend contacting them directly if possible and if that doesn't work, go with the contract company. I also heard that the other airlines are also hiring.
If however, you think that any of the airlines will hire you with 300 hours total time and then put you through their type program, you are living in a dream world. Unless of course your lucky enough to have Filipino parents. Now is one of those magical times in the annals of aviation history that, if one is Filipino, and wants to be a pilot, the opportunity is there if you have the drive and funds. It's a very cool time and you guys are very lucky. Take advantage if you can while the door is still open.