Dr Jekyll, the Luftwaffe did use Nitrous Oxide injected versions of the Ju 88 to intercept Mosquitos. Latterly they used specially adapted versions of the Me410 and He 219. The He 219 I believe was the first aircraft to shoot down a Mosquito in night combat over Germany.
Binbrook, I have not heard before of Flight Engineers before being taught to use the Link trainer. (Although I stand corrected as part of a FE's duties were to 'act as second pilot....' Although like I said, a number of Bomb Aimers were failed pilots). Most Link training was done at specialist schools or on Squadrons. There were some Link trainers, which allowed Pilot/Nav and Bomb Aimer to train together later in the war.