And if so....how?

(and if so...will they be placed in the same position as the others...or will I have to re-position them?)

I don't think you can copy layers ? at least not in the way you are thinking.

But you can select frames or a range of frames and then copy/cut frames.

In the new document you can then paste frames. It has a lot of variations
depending upon how you many you copy, if there are multiple layers, what area
you select before pasting and so on. It would take a lot to describe and I'm
not sure I would describe it properly.

Generally just give it a try and get an intuitive feel for it. The choices are
available from the Edit menu but also from a right click.

It is also possible to slect and edit multiple frames so if you do need to
move a bunch of things on different key frames that is also possible.