So I did it, YARR!
I just DLed the L1 stuff again, copy pasted the Enemy Unknown folder and it works very good. Do I need the OXCE, too? I think not, as the helping friend that gave me the clean install instructions, Ashghan (TYVM), would've mentioned that.
TYVM, DIOXINE & CO., YOU PPL GO TO HEAVEN FOR THIS:) Man, what a King's load of FUN!
One question. The "!Some Mission" research topics have this "Affects the game (progress?)" note. What is that about? Adding new missions?