[Al Skierkiewicz]

Well,
The best suggestion so far is the X-10 system. If you look around (I think Radio shack still carries the line.) They have a remote that will turn the lights on from anywhere you are near the house. You need the base station and a controlled light switch, about $30 or so. I know that Home Depot had a remote control switch they were selling a year or so ago made for turning lights on the outside of the house or garage on/off. I believe the selling price was $18.

As to the Ohm's Law questions...For the most part it is not applicable in this situation. Remember that power is the quantity consumed in the light. Say it is a 100 W light bulb, than the current is less than an amp. (Remember we are talking 120 volts not 12 volts) The incidental current changes supplied by multiple paths are going to be negligible with such a low current. The change of series resistance will not be enough to change the light output where you would notice it.

Safety, safety, safety always. Adding switches is not a big deal in the scheme of things, but when you start talking about multiple paths and the possibility of a switch near the bulkhead (possible wet location) then you have reached the point where a pro should be consulted.