#1
I know it's bad for guitar speakers to play a bass through them, but are the frequencies safe if I play an electronic drum set through them?
If you burp, fart, and sneeze at the same time; you will die.
#2
I have no idea, but I wouldn't try it if you don't wanna' hurt your amp.
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Don't be afraid to care"

Fender Strat/Tokai LS80>few pedals>Orange Rocker 30
#3
It shoudl be fine... Just plug the electronic drums into the Effects loop return so that the preamp of the guitar amp doesn't flavor the sound at all.
#4
No, bad experience with this.

If the eq is messed with on the drums, youre fucckered