First, what is the power rating and impedance of the sub? Is it dual voice coil? If so, what is the impedance of each coil?
I really don't get the second question. Plate amps usually have hi-level inputs that you can route your main speaker wires through and it picks up the signal from that. Also, they usually have a low-level signal jack (RCAs) if your receiver has those types of outputs. There shouldn't be any kind of delay worth considering since the signal is not being carried by squirrels or something like that.
