Syon

They do have buffs for party members but they have their own set of buffs as well. Forget what you know about buffs from old L2. Again, pick the class you like and start playing. Also, a quick search on youtube will give you plenty of info about this version.

Forgot to answer your question: any class here deals damage and has self-buff. You do not need a buff character following you all day. Pick the one you like and have fun.

You don't need a party to gain experience here, but you will need a party or clan to enjoy all that it can offer. Yes, spending money will get you there faster, but you can also have fun like all the other players without spending a single penny. However, you will need to have good trading skills.