Yes I sometimes noticed this and I was debating if I should crank up the exposure a bit before capturing, but that would affect various devices differently. In normal conditions this difference shouldn't be too big, so I'm inclined to say, learn your device and adjust likewise, or later in software.

This happens even in professional SLR's where the screen (or various computer screens as a matter of fact) display the image a bit differently.

The accelerometer stablization hasn't made it to the N900 yet but it will (as soon as the autobuilder is back up). Also you can expect some more stabilization options too.

Fcamera still has some features that ρcam doesn't, like hdr capture.