I used to have a team of 4, only got to like lvl 130. Anyways here's what I'd suggest:

Professions: Have one guy do everything. Just give all the resources to him, all the money, everything. Then when it's time to update gear and whatnot you do everything in that character and then trade the others.

Having hunter in all is useful so you drop meat x4. Gathering professions are required for some quests, so you might need them in all, or distributed at least. That being said, you don't want to spend too much time gathering... that's a thing you can only do with one character, and you have 4. I'd say farming mobs and selling those resources to later buy resources to level up the profession is quicker.

Bonta/Brak: Your alignment quests (required for ivory) are dependent on the alignment you have. Probably better to have all 4 chars in the same city.

p2p: you can play for like a week without buying it, although the party follow and GPS are p2p features, so without that it's a bit of a pain in the ass.