Required for Dual Guns?

Another thing, I also heard you can't actually equip Bullets?

You don't equip them; you use the Reload skill with them.

I'm lost at how the ammo works with them... Its not the same as regular Missiles?

You have an ammunition bar under your character while a gun is equipped. You reload that bar with bullets. Without ammunition, you cannot attack.

Mm, its one bullet per reload, rather than x bullets per reload for the full canister?

Yes, 1 bullet will reload an entire dual gun's magazine.