Permanent Resident visa ...finalizing steps..questions

There is nothing different to fill out on the plane, just do the forms as you usually do.

What ever documents you presented to the consulate in the US should be in the Mexican data base by now. I would not rely on it though. Bring the same documentation you presented at the consulate with you just in case. Rather have it and not need it, than need it and not have it.

Immigration office here can take hours so be prepared for killing most of a day there.

Welcome to Zihutanejo.