Why does my horn beep once when I unlock it using key in door?
 

I searched and found info on two beeps but my boxster does one horn beep when I unlock it using the key in the driver side door. (The fob part is broken). Does this mean something is wrong? I’ve never heard of a car beeping when it is unlocked.

Also, I notice the dash lights stay on after I park and shut the engine off. Will this drain the battery? If I use the key in the door to lock the car then the dash lights go out.

This has happened to me as well. Also have a broken key fob. It seems to be linked to the alarm system and how quickly you open the door after unlocking the car. Now if I hear the beep when I unlock, I lock and unlock the car again.

Get a copy of the owner's manual and read the section on the alarm. Then read it again... and again... I still don't understand the subtleties of the system.
You can find an owner's manual on line if you don't have one.

Glovebox or armrest storage kid are open or unlatched