At present, we do not have a .pap or .lap importer in Animation Paper. This will come at some point. However, it will not be much different than importing the layers one by one as sequences of png’s (after exporting the png’s from PAP). This is how you can do it now in alpha 2.
Internally, drawings are structurally completely different in AP compared to PAP. This gives us a lot of advantages, but it is also the reason why we can not just load old PAP files.
About the “stack of selections” – we do not have a way to bake or clear this. We might think of a way in a future release.
The floating selection is fundamentally different in AP compared to cutouts in PAP. In AP the floating selection sits in its place. So when you pick it up from one frame, you can just leave it there and stamp it in the exact same position in another frame.
If you need to move and place your selection very precisely after all, you can zoom in and move it with your pen or mouse easily on a very detailed level.
If you still feel the need for a nudging feature, please let me know. Then we’ll consider it.