#2
In addition to the speaker out, you can run a cable from the slave out into the input of another amp.
#3
Its so you can have multiple heads - like Metallica do in live shows
My Gear :
Fender American Strat in Metallic Red
EHX Big Muff
Boss ME-50
Boss SD-1
Fender 15 Watt Amp (Upgrade soon to a Marshall )
Red Furry guitar strap

John Frusciante - The Greatest Guitarist EVER
#5
well basically the slave out goes into the input of another head (i think anyway) and you can add more and more heads etc etc.
My Gear :
Fender American Strat in Metallic Red
EHX Big Muff
Boss ME-50
Boss SD-1
Fender 15 Watt Amp (Upgrade soon to a Marshall )
Red Furry guitar strap

John Frusciante - The Greatest Guitarist EVER