I have one question. I've heard some people say that some lifestyles are almost useless unless you play as a certain other class. Like Alchemist is pointless unless you play as a Magician as well. I plan on playing with all of them, but I'll use some more than others, so is this true?
Hm... Alchemist can be quite useful, actually, if only because you can make your own SP potions and such (you can also make your own Life Cures). However, it's not really
needed since you can also buy these items. Only thing is that if you're an Alchemist and you're good enough at what you do, then you can get Super SP potions and such, which are things you can't buy.
Alchemist complements Magician very well, because Magician is very SP consuming. If you're e.g. a Paladin and you run out of SP, then you can still fight, it's just that you can't use any special moves. If you're a Magician, however, and you run out of SP, well, then that's a problem. So as an Alchemist you can create your own potions and always have a stock with you. Which can be useful in any Life, really, as special moves use (a lot of) SP.
In general, I'd say it depends on what your interests are. Like Carpenter can make furniture, which is nice, but not something I'm personally interested in. They can also make a staff for Magicians, but the best wand is actually the DLC one, so it's not like you really need Carpenter for that. Blacksmith can make swords but the best sword (though it's up for debate, I guess) is also the DLC one. They make the best armor, though.
No Life is really and absolutely needed, but no Life is completely useless, either. It's nice that you can switch between them and play the game how you want it, because that's what most important.