Crop preset unit is not decided by the units in Preferences or resolution. It is dependent upon locale in which you installed elements. I don't have complete list but for USA it is inches and for most european countries it is cm. So in which locale did you installed Elements.
Installed for France (PSE12).
The problem is that the options for the crop tool are useless. The ' File / new empty file' creation dialog is much better and the print dialog is very rich.
There are other complaints here about the impossibility to save a custom preset.