1) I have heard a rumor that the (2) versions are not compatible. (Ex. Open file in 11.0.1 and save, now 11.0.0 can't open and work on it). Any truth to this?
You can open an NX 11.0.1 part and save in NX 11.0 with no loss of data. However, if you use functionality that was introduded in NX 11.0.1, and open that part in NX 11.0, you obviously will not have access to that functionality. In CAM, if you don't edit or save an operation like this, you are fine. But if you edit an operation, then the "future" functionality should be safely removed from the operation.
2) I know there is a log in the file of when it was saved, by whom and what version they were on... I've seen it.
Can't find it now. Does anyone know the location?
Aside from the part history mentioned above, there is also an attribute GENERATED_ON assigned to an operation when it is generated, so you can see in what release individual tool paths were generated.