Tours in the philippines

I want to go to the Philipines with some friends for about a week.

Although we don't know where to go, i mean, which islands to go to because i heard there´s many many different islands.

so my questions are:

We have a low, student budget and we want nice beaches just to hang out and relax during the day.

Which one(s) do you recommend?

How do we transport from one island to another? by boat? by plane? is this expensive?

thank you very much