Yeah that's the thing. I don't have a clue what I'm looking for ... when I look for relays on Mouser of DigiKey, I get these large things for switching high and low current. Seems overkill. And while that's a DPDT switch, I'm using two of them (one at an input side and one at an output side), so if I can get a 4PDT one with a single control signal, that would be much better. I may be reaching too high here ...
Probably not but you can use two DPDT relays with their coils wired in parallel and driven by a single switching transistor that then can be controlled by a single arduino output pin that will give you 4PDT action driven from one signal.
The physical size of a relay is usually an indication of how much current the contacts have to handle. You haven't stated but if they are of non high current signals then lots of small DC relays will work, for example:http://www.allelectronics.com/make-a-store/item/RLY-532/5-VDC-DPDT-MINI-SIGNAL-RELAY-2A/1.html