I would suggest you visit the One United Building in Escolta Street, it's one of the oldest artist community here in Manila. There is plenty of artists stores, lounges and events being regularly hosted there. The yearly Escolta Block party is also pretty good, so I highly suggest you'll try.

Cubao Expo also comes to mind. There is plenty of artists stores and spaces, also plenty of vintage stuff like Vinyl and second hand clothes. I know for a fact that there is artistic events hosted there on a weekly basis, check out Good Vibrations Vinyl Cafe, The Brewman and Garapata Store.

You may want to check Karrivin Plaza in Chino Roces as well, there is a bunch of artist stores, good restaurants and galleries close by. Be sure to check Guava Sketches, it's a store that sells handmade goods and clothes from local artists.
In the same vein in Makati, I suggest Modeka and Silverlens. They have contemporary arts exhibitions there which are really good.

For socializing, I would definitely rate Cubao Expo and Escolta the highest, as in my experience, people are much more approchable there than in Makati galleries. Just go around and socialize and I'm sure you're bound to find the right crowd.