New player with a few questions.

[Niwashi]

You should definitely unlock Summoner, Scholar, or both. After that, any advice will depend on which you go for.

As for the gear appearance question, there is a feature (referred to as glamour) that lets you apply the appearance of one item onto a different item, but it can't be unlocked until you reach level 50 on at least one class. (Once you get that far, the quest to unlock it is "A Self-improving Man".) Until then, you have to settle for a gearset with your best stats for dungeons or difficult quests, and perhaps another better looking one for simple running around content. Oh, you do get to at least dye your equipment earlier if that helps. (The quest for that is at level 15, Color Your World" in Western Thanalan.)