Right, Mythbusters style :)
It's definitely doable. I would try to let gravity do most of the work, so you only need to pull some things or let go of things.
Electronically, the place where you want to go is "relay". It's a magnetic coil that pulls another switch. Controlling the coil is easy to do from a computer 5V, The switch can handle anything from 12V to 220V. Relays are slow (order of 50msecs iirc), but quickly enough :)
The circuit with the magnetic coil is completely separate from the circuit of the switch, which is very good for not blowing up your computer.
Check out the electronics shops, near controlling devices or home automation (DIY rather than polished companies plug-it-in, although, if you never did any electronics, that may be a simpler but more expensive solution to you). Also, read forums/wikis about home automation.
As for making things move in the real world, electro-magnets would be one way, it's like normal magnets, but they have an on/off switch. Turn off the power (relay!), and no magnetism any more -> drops -> pulls rope + weight -> opens door, kind of stuff.
Shop in the electronics store, and see what they have. Make sure to put in over-voltage protection. Devices with coils (electro magnets, motors) produce big voltage peaks when switched on or off, and you don't want that near your relay contacts, it gives sparks, and burned contacts.
Last but not least, think safety! Elevators or electric winches, or any other physical device continues to move even if your arm, leg, or other body part is at the wrong place. Your clothes may get caught in the mechanics, you may get caught by a swinging rope in some way. All these devices are generally stronger than you, which means you will loose in a very unpleasant way. Have emergency switches everywhere that disconnect power, always have two or more persons in the room, increasing the odds of being able to reach an emergency switch in case something goes wrong. Remote-controlled means things may start to move at any moment (computer looses power or is badly programmed -> all devices trigger!, power-failure -> all devices trigger!)
As for help, I think you need to go to the classifieds, although in your case, it may be better to find someone with home automagication knowledge.