Rogue archer is godlike, especially in the early game where early unique bows are far more powerful and more common than unique daggers.
Later on good bows only really come from the boss drops, and stronger daggers become more plentiful, so by the end game rogue archer is more of a support class.
Slightly. With the skills there are it can dish out a hell of a lot of damage, and a lot of the synergies from the dual-wield work just as well with bows, but in terms of pure damage the bow skills are better for crowd clearing whereas dual-wield is usually for nuking the shit out of single enemies.