Thanks to prixat for telling me that,

the Info Palette open it will display the size (and position) of the crop.

That will be a very handy way to do a freehand crop and obtain either a
target size or a target aspect ratio. 

(I'm beginning to get the idea that I should try to actually study and
really learn photoshop instead of just jumping in, using it, and
seeing how much trouble I've caused myself ... ya think? ... LOL)

--
Martin