2) Yes. If CAD fails - no fuel indication available !
You will stay only on red warning lights on Warning Panel - LOW FUEL 1 (and LOW FUEL 2), which means that you must be on ground within 10 min (or 8 min in the earlier models)
...and ENG 1 will stop 3-4 minutes after that 10 minutes...and ENG 2 after next 1 and half min!
JR