I think it’s time we shake things up a bit in TSW4 interesting related. So let’s look at our track engineering train, class 66 RHTT. I think some track engineering machines should have a spot in TSW4, hence rail tampers. Also an add on for the ECML. I personally think the Grand Central class 180 Adalente
Arriva own Grand Central and they aren't too keen on giving out a license unfortunately. Although, despite that, the 180 would be better off being used somewhere than the ECML (on which it could layer instead).
Possibly, yes. Would be better for it as they usually run fast between King's Cross and Doncaster with an occasional Peterborough stop.
Bradford to Doncaster or York to Sunderland probably. Having them just on the ECML makes little sense as they don't serve any stations between Peterborough and Doncaster, and sometimes even skip those stations altogether.