You can't beat going with Cathay and it looks like you got a good price.
I can't comment too much about where to visit in the North because (as you know) I always go to Cebu and the Visayas.
I worked with a Pakistani guy who went to Boracay every year and loved it but it is more expensive than other, less developed places.
What to wear? I also take a pair of "travel pants" for the flight and whip the bottom of the legs off when about to land in the warmer countries. Take a couple of pairs of shorts and some T-shirts and short sleeved shirts. No doubt you will hit the malls and buy some souvenir T-shirts although the prices last November were far higher than when I first went to the Phils in 2004. Also if you go to a resort or touristy place you will be pestered constantly by T-shirt sellers and you'll probably buy a few.
Take a decent pair of sandals with you. I found it hard buying larger sizes and quality in the Phils is variable.
Jet lag might be a problem. I usually only get it coming home but last year I got it at both ends. Just be prepared to write off day one in the Phils for trying to sleep.You may struggle to sleep as you'll either be hot and sticky or cold due to the aircon, or kept awake by the noise of the aircon. The jet lag will prevent you from sleeping for the first couple of nights anyway.
Make sure you have a number of bank/credit cards to use out there.You should be able to withdraw cash from Visa cash machines. Best to take some Pesos with you and if you do go into the provinces you may have to take enough cash for your entire stay.
If you need any more advice, pop round and ask.
