Sup,
Yes PA is needed unless you have 2 PCs (1 for ech char), WC/OL are more than welcomed indeed.
About the DA/SK comparison, they are both good in general. When it comes to aoe xp they are pretty much the same,
but when it comes to solo I do believe that SK is the king of tanks, due to the cubics/hex and the high dmg due to its race.
DA on the other hand is not that bad due to the panther, but when it comes to pvp, DA is the boss, check a pvp video or so, to see what a DA can do.
Cheers