If you decide to disconnect the battery, be certain the front hood/frunk cannot close. Put a large blanket or something in between the top and bottom. That way you assure access to the battery when you want to move the car again.
My car is a 986. I have had my battery out of the car for a week or so. You will lose the radio codes. Make sure you have the card with the factory codes. Also, I believe the OBD stuff is reset to defaults. As a result, I find it difficult to start the car the first time out. The engine also seems to run imperfectly for a bit. By the second day, I have no issues. If you have a newer car, there may be other issues that do not affect my situation.
I cannot speak to the charger method.
In addition to charging, others make a point to put the car on jack stands to prevent wheel flat spotting.
Still others put cloth bags of mothballs in the two trunks, the interior and in the engine bay to discourage critters from taking up residence.
Put Stabil in the gas.
I recall seeing a long term storage punch list some place.