I have recently purchased a new home. The tracklighting that was installed has left brown marks that look like burn marks on my ceiling. Should i be concerned and what might have caused it?

Probably a simple question..... I have 1 switch in the bathroom, it controls the lights over the mirror as well as the vent/fan in the ceiling. I had the same setup in the other bathroom, and installed a double switch no problem. The problem upstairs is that in addition to the light/fan/power wires, theres also a wire bringing power to the bedroom hooked up to the switch. As I look into the box, there's romex wire coming in from each of the top and bototm corners. Seems logical that the two coming in from the top are the fan and light, and the bottom 2 are the hot wire and the one bringing poewr into the bedroom... On the single switch, the top right wire goes to one terminal, and the other 3 are merged into 1 with a wire nut and attached to the other terminal on the switch... Can't figure out how to wire them onto the double switch (with 4 terminals...) Help!