Ahhh, that explains why yours has a big heat sink on it, mine's the previous version.

You would need both leads to operate the needed two channels. Power is supplied to the unit by the rc connection leads.

I don't personally use a switch as when the powerbox is off so is the lighting unit, I can't see any reason to use a seperate switch, personal choice I guess. Then again which powerbox are you using, is it SRS or are you using a completely seperate rx?