Porsche 911 Carrera Front Bumper Wheel Liner Replacement - 996 (1998-2005) - 997 (2005-2012) - Pelican Parts Technical Article
You'll probably need to replace the horn. The procedure to get the bumper cover off is at the link above. It is actually not that difficult if you take it slowly and follow the instructions...and remember which screws go back where.
While the cover is off, take the extra time to clean the debris between the A/C condensers and the rads. You won't see anything unless you separate them and back wash the sand and debris out. You will be surprised at how much junk is there. Just remove the rubber shrouds for cooling, then do the 4 screws holding the condenser to the rad and pull away. You do not have to disconnect any coolant or a/c lines. I used some simple green soap to clean the fins and lots of water.