Psychic Dark Half

Do the rounds need to be consecutive? I'm assuming they do not, but the text does not make that explicit.

It is pretty much exactly like a Barbarian's rage, but all magical and stuff. I am fairly certain you do not have to use it consecutively.

Given that there's a mechanic for changing back to normal, I'd say that the rounds definitely don't have to be consecutive, unless you flub the concentration check.

The psychic can return to her normal self as a free action, but must succeed at a concentration check with a DC equal to 10 + 1/2 her caster level. If she fails, she stays as her dark half and can’t attempt to change back for 1 round.

It is pretty much exactly like a Barbarian's rage, but all magical and stuff. I am fairly certain you do not have to use it consecutively.

Yep. The rounds don't need to be consecutive.