That drain plug is easy. Take it out and wrap about 10 turns of teflon pipe tape on the threads and screw it back in. Tighten until the leaking stops and be careful not to overtighten. As for the motor, they do run hot especially if in direct sun. Think I remember 140F or so on mine with an IR thermometer and that's inside a poolhouse. Could the water just feel warm because the air was cool? Only way a pump could heat water significantly is for the flow to be almost blocked and pumping only a trickle then all thre energy from the motor goes into heating water rather than moving it.
Al