hehehe, Jesus pose...
I don't know much about performing live toerh than playing only 1 instrument at a time,but I would guess a good place to start would be to practice practice practice, perfect your skill/technique and work with what you're have and see how you're able to pull everything together in order to give your show some substance. Your style will come through, and so will your poses and movements on stage - who knows one day, other budding live musicians might be saying "yeah man, just do the Quantum-Celesta pose on stage!!" ;)
As for The Chems, I certainly don't know how they pull off all that magic on stage. It's all electric spaghetti and stacks of gear with twinkly lights and slider knobs - a symphony of gear that they magically orchestrate in almost a multi-tasked, tentacular way. I don't know how any of that stuff works from a techie point of view. But the Chems have been asked in the past how much stuff is pre-sequenced, and how much is improvised live and they have said there's quite a bit of jamming going on up there on stage. And if you listen to bootlegs of live gigs, you can hear how the shows vary from set to set - even if those variances are subtle.
The Chems also have a great freakin crew with them on the road, these people know what they're doing and the show couldn't go on without them. Given that the visuals are a large part of the live Chemical experience, my guess is a lot of care has to be taken to ensure the songs are in synch with the lights and what's going on with the imagery which would lead one to believe that a lot of sounds and data are brought along and triggered by Tom and Ed at just the precise moment in the songs. Some visuals in the show are fluid/loose and I would imagine allow more musical flexibility for "jamming" and mixing things up a bit. It also helps that Tom and Ed are practically married to their gear, and they know what's what like the backs of their hands.
Anyway. I don't know what the hell I'm talking about, so don't mind me. :P