Hi everyone,
I grew up in Quezon Province and my mother was a Filipino teacher. Tagalog is the regional language of most of Luzon, the biggest island of the country, and of the islands of Palawan, Mindoro, Marinduque, and Romblon. Filipino is the national language based on Tagalog. We speak Tagalog in Quezon and it is slightly different from Filipino in terms of conjugation, grammar, and vocabulary. For example, we would say "Ano ga ang ibig sabihin nire?" instead of "Ano ba ang ibig sabihin nito?" for "What does this mean?" Moreover, within Quezon Province, we have varieties of Tagalog, but that's minor. I'd recommend you learn Filipino because it is the standard form for national communication. It's the language spoken on Filipino television shows. You should also consider where you plan to stay here, because in the central and southern part of the country they mostly speak Visayan languages, which are very much different from Filipino. Almost all people understand basic English I'd say. I haven't seen good didactic material in learning the language but you should be able to manage here with some simple essential phrases for the market, transportation, greeting friends, and asking for directions. People are generally friendly and helpful.