OK Harry, like you I never give up, so what I always do is look at it in a logical way:-
1/. It worked on 10, from the CD with your original profile
2/. You inherited 11 Pro and it hung from cd on 'components' - so there are differences between 10 and 11 causing the problems. It cannot be fat32/NTFS as 10/11 should be similar. Reading about 11 one of the main upgrades/differences is security, is the security blocking the download? as I don't have 11 (still on Dos) I can't see if it has any controls over downloads, perhaps investigate.
3/. Rather than get overcomplicated I would stick at first with the cd only and try to get it working, in theory the easiest way. So I would wipe everything clean and start yet again with this path, trying to sort out the missing components issue.
4/. If this fails then wipe it clean again and go down the Steam path again with the new knowledge gained, are you sure you've eradicated patch 1.8? by not loading it?
I'm no expert but have solved things like this in the past by working in a logical way, we'll get there my old buddy.