Hello Michael :)
The answers to those questions are:
The green screen was (I guess) pro grade. It was grey until it was illuminated by a ring of green LEDs mounted around the camera lens so I don't think it could have been lit any better.
I've got a screenshot here:
The footage was shot on a JVC700 Mini DV camera. A very expensive camera (ex-TV I think) but still only 720x576 (PAL). Does resolution have an impact on how well you can pull a key?