I just wanted to know if the bonuses translated to dual-wielding as well, or is it pointless to even get if you aren't going to only use one weapon at a time?
The perks that do not apply specifically to dual wielding apply to attacks made with two (2) one-handed weapons, one (1) one-handed weapon and/or one (1) one-handed weapon and one (1) shield. The dual wielding perks give those fighting with two weapons additional bonuses to compensate for the lack of defensive shields/magic. Two weapon fighting is all out offense and receives all of the benefits from the other perks found in the one-handed tree.
The only "exception" to this might be Critical Charge as I seem to attack with only one of the two weapons I have equipped. It gives you a nice movement and damage bonus though, so I still think it is worth taking as a two weapon fighter.
Side note: I highly recommend taking this perk because the decapitate animation is both cool and satisfying.