Release Date - Sorry I can't help you on that
Bodyshell - I was using the JC shell out of personal preference, to see whether the style of shell makes a difference. The design is set and is the shell that was shown at the toy fair.
Diffs - Not gear diffs. The boots are been used to evaluate how well they reduce wear of components.
Towers - No idea whether the production will be multi hole or not. I assume it will depend on how testing goes.