The Hull Trains 180 have the dynamic lines First livery. The Grand Central ones are in black livery. Two East Coast 180s are in First Great Western livery, the three subleased from East Coast to Northern have had the First branding covered with Northern's purple colour.
If you mean Bounds Green dept, it would most likely have been East Coast's 180104.
Yes, it's EC. The 180 is now hidden by a GC HST though.
Permanently? Its always hidden by one for a couple of hours per day.
Could be, I don't know the depot names on this route! But it's clearly an EC depot. Plus theres only EC trains in there, FCC have a depot at Hornsey I think?