#4
The hell is geater when this particular magnetic pickup (but I should be sure, all the cheap ones, too) placed on a classic guitar the amp detects the sound!!! (Watch it at the beggining of video - and later the simple explanation).
#5
Sorry, I'm not watching 13 minutes of explanatory vid, but I've been using microphonic magnetic pickups for many years. Here's an example, on my old National reso:

http://www.soundclick.com/player/single_player.cfm?songid=6719048&q=hi&newref=1

This recording is from the amp, no direct acoustic content at all.