Not sure on the first two, havent played nightblade much.
But yeah as mentioned above check alcasthq, he has the best guides, or deltias gaming.
As for #3 the skill bar is 5 skills and an ultimate. But you get two bars, one on main hand, and one for back-up. So you can have a total of 10 skills, amd two ultimates split across two bars. If you want to switch between the two, you could get the exact same weapon for both bars, and then use it that way if you wanted to.