Lots of good answers already. Hopefully this one doesnt lower the average.

1. Questing should be fine. In general, its a good idea to look at your gear every 10ish levels(1-49) at first, then start checking every 5 levels(so 50, 55, 60, 65, 70 - bold levels are the ones with the biggest jumps). If anything looks like its way behind, check on it. In some cases the difference wont matter(a bracelet only getting 1 extra point of your main stat shouldnt need to be upgraded yet), but checking doesnt hurt. In general you want to prioritize weapon, then body/legs, then head/arms/feet, then belt, then jewelry.
2. Starting over an a NA/European server wouldnt be a bad idea assuming you live in one of those regions. A lot of the content in the game allows you to team up with people from outside your server, so what data center you wind up on matters more then your individual server for most things.
3. A class is what it is. Every class has damage abilities and is expected to contribute some, but a white mage remains a healer and a paladin remains a tank. This game doesnt offer many ways to customize your classes battle capability. Instead, you switch your capabilities by switching classes. As others pointed out, your character can level as many classes as you like.
4. Not really a thing.
5. In this game race is 99.99+% aesthetic. Every race can play every class to essentially the same level. Some jobs will still be more popular or in demand then others, but very few people will care which race you play(and those who do care will be for aesthetic reasons also).
6. Part of the set of quests in your starting town will involve you meeting the people at all the guilds. Most of them will have some minor task to ask of you(eliminate some pest, deliver some message, etc). You can do these quests as a "getting to know the area" sort of thing(probly what the devs intended them to be), or you can save them and use them later on to help level up a secondary(or tertiary etc) class. Once you reach level 10 and complete the class quest from your primary guild each of the other guilds will offer a new quest(something like "So you want to be a goldsmith"). These are the quests to unlock the other classes and your ability to switch to them. Do as many or as few as you like. And if you do find yourself enjoying another class more then the one you started with than you can just stick with the new one. Or go back and forth. Or whatever.

Other tips: The most important thing for this game is to follow the main storyline quests. This is a story-focused MMO, and most of the game areas and features get unlocked as you finish certain checkpoints in the main storyline. That doesnt mean you have to love the story(it certainly helps to like the story but there are some people who skip cutscenes and dont read quest dialogue), but if you dont do the quests you cant advance. Second most important are your class quests, as many of these unlock new and more powerful moves you can use in combat. There are additional quests that unlock optional features(the casino, the glamour system, etc) and these are all good to do as well. You can tell all these quests apart because they have different icons. The main quests have a meteor shape to their quest bubble, the class and unlock quests have a plus added to the quest bubble, the rest of the quests(the ones that just provide lore, exp, and maybe a piece of gear) have a plain oval bubble.

Best of luck, and welcome to the game!