goofy question about wireless flash...

your all probably getting sick of my flash questions...

How exactly does "wireless" work?
I currently have a DS... moving up to K100 soon.
Looking at getting the 360 or 540.

How is the flash triggered wirelessly? Does it need to be triggered by the onboard flash? If thats the case it kind of defeats the purpose for me as I don't want any light coming from the camera.

To avoid this do I need to by one of those little transmitters and put it in the hotshoe?

Basically what I would like to do is have a flash unit that operates away from the cam. One of the things Id like to do is experiment with macro water drops etc and a wireless flash would be ideal. That being said, maybe I just need to go with a long cord connecting the flash to the cam.

confuzed

Jason