I tried to replicate your problem and I had no trouble with my print. A couple of things to check:
1. When you look at the Image Size after cropping, does it say 2.5 x 2.0 inches at 150 pixels/inch as it should?
2. If so, then are you sure the "Scale to Fit Media" box is unchecked in the Print dialogue?
If these two things are as they should be, I don't know what could be happening. Maybe someone else can jump in here.
As for printing too dark, unless your monitor and printer are profiled, you will just have to use a Levels adjustment layer in PS to lighten the print by trial and error.