I have a spent a while diving in the Philippines. You mentioned PG...did you mean Sabang? Both are pretty close and easy to get to from Manila, Van/Banca is easiest about 2 1/2 hours by van depending on Manila traffic and little over an hour by Banca from Batangas. You also mentioned wreck diving and for that you want to go to Coron, Coron has more than wrecks but vis can be a problem. I also like Alona beach, there is more there than just Balicasag. For whale sharks you go to Oslob about a 3 hour drive from Cebu, you can dive there but it's better to just snorkel with the Whale sharks IMO. My favorite is Coron, because I like wreck diving, but there is also 2 lakes and some nice corals. Most places will cost ~2600-3300 pesos for a 3 dive day with lunch. When you get to Manila you will probably arrive at terminal 1 and most of the local flights are from terminal 4 which you will have to take a taxi (metered) or the bus to. Also very important contact an operator in the area where you would like to dive and let them know your intentions. I did this in Coron and dove solo for 3 days without having to pay a Banca minimum. I have spent the last 3 years diving the Philippines with 164 dives there. I live in China so I fly in and out quite a bit. If you would like information on any particular place just let me know and I can give you names and places or pics.