Assuming you have a 986 (as I have no experience w/ 987s) sounds like your ignition switch is bad - especially w/ the note of key being hard to remove.
A bad switch will drain the battery as it doesn't shut things off as it's supposed to when you pull the key. Plus the #s you post suggest alternator is working. If the alt had a real charging problem and you had a bad battery, it most likely wouldn't run after a jump and disconnecting donor vehicle.....
Here's a link to replacing the electrical part of the switch
Part # needed is: 4A0-905-849-B
It's a common part across VW and Audi too so shop there (as some P-dealers will try to tell/sell you on replacing the whole sub-assembly = $$$.$$). ********************************az sells the part for $8.78
********************************AZ Link to Part but you can pick it up at local dealers for ~ $30
Keep in mind too that our batteries (OEM) are not sealed and need topped off frequently (w/ distilled water). Proper maintenance will keep a battery for a long time. I shouldn't say this but..... the battery in my '99 is the original (built in 11/98) so it's almost 10 years old. I store it in the winters on a maintainer and top off the fluid just before and after storage as well as check the fluid every month or 2 in season.
Good Luck
