Re: As for that time...
"Interestingly the computation time is not included for human solvers - they get to examine the cube beforehand, and work out what they are going to do. So the 4.9 second record is simply for executing a series of pre-worked-out moves, with a few (very short) calibration stops along the route."
Which raises the possibility of a variant of the speed solve competition: from a blind start, thus taking into account on-the-spot mental solving as well as the mechanical manipulation into the time.