I fear that this is not going to be that type of dig! As you note there is probably a lot more to be discovered but a road tunnel is unlikely to be it
Yes; however the archaeology extends far beyond the stones.
The interesting thing for me is that such calendar circles seem to be associated with 'cattle cultures' which developed at various times in the fourth millenium BC; similar circles - with associated cattle bones - have turned up in Orkney , Calanais, France, Spain and - you guessed it - Egypt.