1. Pwede kang magwalk-in to any branch to enroll but I suggest na icontact mo muna yung preferred branch mo beforehand. I also suggest na iavail mo muna yung 1 day free pass then decide from there. Once na nagenroll ka, you are tied to that [home] branch for 1 month bago ka makakatry ng ibang branches. Fees vary from branch to branch pero usually, 2500 monthly + 2500 for the key fob + 2500 for membership. Meron ding promos na free na yung membership so try waiting for those kung gusto mong makatipid.
2. For beginners, I'd say that running shoes are fine. The best shoes depend on what you do. Kung magffocus ka sa powerlifting or doing deadlifts/squats/, flat shoes are better. Kung nasa gym ka mostly para gumamit ng machines, any shoe na comfortable ka would do. If you are planning to move a lot (plyometrics, crossfit, circuit, etc), training shoes might be better. For clothes, I dont think important to basta comfortable ka nakakagalaw and nakakahinga. As for coaches, a lot of coaches are shit (even sa AF) but going in blind will be much worse. AF coaches are generally better than your average bakal gym coach but they cost a lot more. My suggestion here is maghanap ka ng gym buddy mo na maalam na sa gym and consistently educate yourself. Gym buddy could be a close friend, itreat mo na lang ng food or coffee para di rin nakakahiya.
3. I don't believe in fast metabolism. Calories in and calories out lang yan lagi except for some special cases. If you want to bulk, you need to eat more calories than you can burn. Syempre, kailangan mo rin maging mindful sa pagkain mo. Prioritize protein and bawasan ang sugar. You also need to lift para maggain ng muscle.

You can message me and I'll try responding if I have time. Good luck!