About the problem connecting to Fiesta: The servers are down, and probably will be until tomorrow.
About the class: Archers are pretty hard til 51, but after that you can "kite" (I suggest looking up a video on that to see what it is.) and get quite a good amount of money that way.
Fighters can solo well, so if you like killing 1 by 1, your luck might lead you into quite a bit of money.
Clerics are pretty good at reserving money, but if you don't find a good party, it's pretty hard to make money due to their weak power and limited attacking skills.
Mages are not recommended for new players because of their weak defense and hitpoints.
Hope I helped.
Threaded Mode