[WAP007]

Hi everyone!
I have a query regarding the sensor on my D90.
I have been taken photos that fill the lcd and doing like a lot of people do, just downloading to my laptop and leaving it at that.
I have taken some photos which i'm really pleased with and wanted to get them printed, so I took my SD card to the local photography shop to do so.
I thought I would just get them printed and that would be that, but I was losing a lot of the photo and the final image wasn't what i wanted.
The guy in charge came over to help and said that the sensor in my camera shot at 12''x10'' so if I shot photos that fit the lcd I would end always end up having to crop them, or get them printed at the 12x10 size ( impossible to get a frame off the shelf to fit), or shoot wide and then crop when printing.
Is this normal?
My friend has a D7000 and what she sees on the lcd is what she is able to get printed without any adjustments.
Another things with my camera is it does seem to over expose when using lighting. It's fine in normal light, but I have done a couple of workshops, the lighting checked with an exposure meter and everyone set there camera to that. Mine had to be adjusted by 1-2 stops to get the same exposure.
Is there something in the menu that needs changing?
Thanks in advance for your replies