#4
If you mean using something like a Dtuna, it fits on a OFR, but an edge 3 and an OFR are directly swapable, so i would assume so. i dont know for sure though

http://www.vanhalenstore.com/page/VH/PROD/guitar/EVH18

has a FAQ on that page and here you go

Q: Can the D-tuna be used on any Floyd Rose Tremolo?
A: It can be used on any Floyd Rose or Licensed Floyd Rose Tremolo with the long locking screw, where the fine tuner on the bridge presses directly on the locking screw.