in the more northern areas in either west or east sarutabaruta (I prefer east but it doesnt really matter) and when you feel those enemies are too weak either try Tahrongi Canyon to the northeast of East Sarutabaruta or if you want to party you could try Valkurm dunes which is a pretty long journey east through Tahrongi Canyon and then through Buburimu Pensinula to Mhaura and a long tedius boat ride away. partying in the dunes is hit or miss though, I dont know if the level sync changed that, doubt it though

as for quests and missions you start quests from talking to NPCs in towns and you start missions from talking to guards by the gate with W.W. before their names

the FFXI wikipedia has more information on the quests and missions.. and pretty much everything

http://wiki.ffxiclopedia.org/