Hi Scott,
I went through the OCU in 65 - 66 and don't recall any extra manuals (I am sure we got the odd precis - didn't keep any - but nothing in book form). The only info was that in the then Pilots Notes (now Aircrew Manual). I think systems operation was taught in ground school, in the sim and on the aircraft. I might be able to answer some of your questions from memory. During my time data link was not available although the instruments had the markers for it (as you saw on the ASI), and I doubt data link ever came into use with the RAF.