1. Ti is about 0.0042g/cubic mm (I think, that's from memory), so 100x100x0.0042 = 42g
2. Much higher power/weight ratio, higher max output. Basically more voltage and ampage in a lighter package.
3. Pneumatics have only really been used successfully by 2 ants (from memory), firstly, Rebel, used the lego pneumatics to make an awesome flipper, which no-one has been able to top for pure flipping power, and Anticipation, which uses the pneumatic system from
www.robotcombat.com. If it's your first time messing with pneumatics, I'd suggest buying some stuff off Ebay and just playing about with it. You will need a ram, storage (an air tank), a valve, a way of pressurising the system (a pump), tubing to connect it all together, and probably fittings such as T connecters, etc. As for making it viable for robots use, the robotcombat stuff is designed for it, however the lego stuff needs to be modified a bit. There was a guide somewhere but I think it's down at the moment, but basically it involves increasing the flowrate by drilling out the input ports on the rams, as there is only a pinhole at the end of them for the air to flow through.
Hope this helps
