The two biggest differences between the AFCI's is that the combination type is supposed to trip at 5 miliamps of current as opposed to 75, and the combination type is also supposed to detect arc faults after the outlet, such as cord and plug connected equipment.
As for your other questions, yes, all outlets in the bedroom (120 volt, 15/20 amp) are to be protected. This includes receptacles, light fixtures, smoke detectors, etc...
