Put stabilizer in the fuel before you park it for whatever time it is before your return. I’d also suggest buying a jump starter box in case the battery is low when your return so you can get it running again.
Cover or not depends on where it is parked? In direct sunlight a cover might be helpful but likely not really necessary.
If you are worried the parking brake might “stick” you can leave it off and put “chucks” under the wheels to make sure the car doesn’t move. The parking brake on my '03 Civic works great and I’d have no issues leaving the parking brake on.
I wouldn’t be concerned over the battery for a 2 or 3 month period. If your parking spot has access to electricity you might consider a “battery tender” charger. There are also solar chargers that will keep a battery charged nicely in Hawaii if the car is parked outside.