Jim - Voc is the open circuit voltage produced by the panel, i.e. what you would read connecting a volt meter to the leads form the panel (under ideal solar conditions) Vmp is the voltage when the panel is producing maximum power, i.e. the voltage when the panel is operating under normal conditions connected to a controller.
If you are using a PWM controller such as the GoPower unit, the panels should be connected in parallel since PWM controllers do not gain output current with higher input voltages. If you had a MPPT controller, there are advantages to connecting panels in series - it reduces current, allowing smaller wiring, and the controller will convert the higher voltage to greater output current. Unfortunately, most MPPT controllers cost much more than the equivalent quality PWM controller so the choice of type depends on the size of the system.
While I'm sure some will disagree with me, for the typical small systems we can fit on fiberglass trailers, it generally is not worth the additional cost of a MPPT controller, but for large systems they make sense.
Cypher - The GoPower controller is a 30 amp unit - if you use the Imp (or more conservatively, the Isc) of the panels & add them, as long as they are under 30 amps you are OK. According to the GoPower site
, their controller is designed for 80 watts - 480 watts of panels. One important note - the GoPower 30 amp controller is used in current trailers - an older version (the GP-PWM-25) may be in older trailers, which is a 25 amp controller.