Ok, so what should I do now?
If you checked the X10 links you see in general how X10 works. The PCS stuff is high end but uses the same "House Codes - Unit Codes"
Start investigating at your end, because we can't at ours.
Are the remotes all X10?
Since you have lights coming on and off with out your action (and I am excluding obvious light triggered by motion detectors) it may have a computer running the show somewhere. If a computer isn't obvious, look for an interface hidden somewhere. Could be X10, or Smarthome (small white plastic box), or something larger attached to a wall, usually in garage, basement, or utility room i.e. Oscelot, JDS, etc. Thes examples can be programmed by a computer and then run atonomously.
As for the floors and furnace, you are talking high power so there has to be some X10, PCS, Smarthome modules controlling power to these units. Have you located anything like that?
As far as a computer program. The X10 home automation interface CM15A and AHP software will monitor the powerline in the home and tell you all the X10 codes on the powerline and the time the code was sent. You may be able to use that to tell you what X10 codes are controlling what lights, fans, furnace, floor, etc. But it will be a laborious project. When something changes state you will have to check the Activity Log to see what the code sent was.