Depends on model year is the answer but in your case w/ a '97, yes you need to input the code for your radio after reconnecting the battery. Post '03 MY, Porsche uses the MOST fiber optic system which no longer required the radio code.
I am having the same issue where the horn works but it goes off constantly when I put the fuse in. If I push the front of the steering wheel the horn stops. Below Releese 78 mentions the retainer frame. I have the airbag off removed from the car. Where is the retainer frame located? I looked at the Suncoast web site linked below and I could not find the part that Releese 78 is referring to and part of the reason I cannot find the part because I am not totally sure what I am looking for. Thanks in advance for your help.