Re: Ceramic pads
Ceramic brake pads are used for a number of reasons, mostly because they handle heat better than organic or semi-metallic pads do. They also tend to be quieter then most standard pads and they produce a less noticeable brake dust on the rims.
The draw backs to ceramic is often a required higher braking pressure and tend to wear the rotor faster than a normal pad will. This is often a bigger problem on softer metals, including stainless steel.
I'd probably stay with the OEM pads for a few reasons, first of which would be that the brake system on your trailer was designed to work with the type of pads it came with. Second, trailer rotors are the most expensive part of the system, ceramic pads may eat up the rotors prematurely. Last, if they require more pedal pressure to stop in a car, how will you compensate for that at the trailer which is most likely using surge brakes which pretty much have a set pressure applied by the trailer's own weight. You may find that the ceramic pads don't grab as well at that pressure.