I have a copy of "The making of the Wrath of Khan" (title not exact) around here somewhere. I think that the original intent during production was that TWOK would be the last Star Trek movie. Mainly since Spock died at the end. I don't remember if the "remember" scene was a pick up shot done later or not. I do remember that it was done on the fly to leave the possibility of Spock returning. As production went along the producers began to realize that they had a winner on their hands.
I know I saw TWOK in 70 mm because I later worked at that theatre. I don't remember what the opening title card said. I believe that it's possible that the title card was different because 70 mm prints are usually struck after the 35 mm ones. You have to create a 70 mm master in addition to the standard 35 mm master. And a separate multitrack magnetic soundtrack has to be created.
Back in the 80's those 70 mm prints were hugely expensive. We had a faulty magnetic soundhead partially shread a 70 mm print of "Indiana Jones and the Temple of Doom" about half-way through it's run. The soundhead manufacturer had to pick up the replacement cost of over $100,000. That was the first 70 mm print I got to build up on my own. I got to learn on "Ghostbusters".