I'm not sure about Dweezil’s setup, but I believe he tours with two; I had the notion that one was essentially a backup.
I could be completely wrong, though – he may be combining sounds. Sorry, that's not much help at all!
Absolutely! Especially since you'll be overseas. (As Hellbat said "That Murphy bastard" is an evil SOB)If I was touring I'd have a back up everything.
I guess it depends on what you can make it through the show/tour with. For me, I bring a Tech 21 Fly Rig and that's OK as a last resort as I'm not super effects dependent. I might want to consider the Atomic Amplifire instead but $600 feels steep. I've never used the Fly Rig but I only gig about 8-12 times a year.