Although not schematic for WS13, this will be close.
http://www.laureanno.com/ws467.jpg
I really don't think the schematic is very close to the WS13A.
yes, I should have been more specific. I meant in reference to your original 3 questions, the 467 schematic "is close". Your questions relate to what I consider the "input" side of the controller chip. i.e. PLC code receiver input, HCUC addressing, local sense, and remote control from traveller. The output side of the controller differs mainly in what is being controlled i.e. a triac (bi-lateral switch if you prefer) or a solenoid. (NOT a standard relay per say). The controller chip themselves differ between lights (triac control) and appliance (solenoid) control. Also X10 has several different chip numbers, but the actual "silicone slab" is very similar to the original 1979 designs, differing mainly in pin out configurations.
The "input" side of the controller for the; 2 wire wall switch, 3 way wall switch, three wire wall switch, (triac and "relay'), "super socket" receptacle, lamp module and appliance module are functionally all very similar. X10 reuses their original design as much as they can (check out Ido's material, where there are plans for turning a two wire wall switch into a three wire with neutral - essentially turning a 467 in to a WS12 with the addition of a wire).
The 467 is a dimmable two-wire bi-lateral switch to replace an SPST line switch while the 13A is a three-wire module requiring a true NEUTRAL connection and acts more like an appliance module -- suggesting a set of true relay contacts in lieu of triac control of the load.
Sure, it is a solenoid "relay" that makes a nice solid "clunk" when the solenoid rotates the cam. Any X10 "relay" module MUST have a neutral since there is no parasitic power available for the internal electronics,once the relay is closed. The 2 wire wall switch derives power from the drop across the triac.
Let's just say a white wire was delivering full time juice to a location where a porch lamp NEUTRAL white return wire was connected to a local bare wire GROUND in a switch box!!!
Well, that sould have made your GFI go nuts.