1997 Honda Accord Radio 15 AMP/Interior Lighting 7.5AMP fus

My Honda Accord's radio and clock stopped working one day. For some time prior to that (after the battery had died, but had been replaced), I noticed that the interior lighting (i.E. The lights by the lower front doors and the general lights in the center and the reading lights.) Along with the sound alarm that would indicate if I forgot to turn my light off, were not working. As a result, I would always forget to turn off my light resulting in a dead battery.

I finally changed the fuses for the radio/clock, a 15 amp fuse and change the fuse that controlled the interior lighting, a 7.5 amp fuse. When I turn on the car, everything was working again. I was happy. But, when I turned the car back on, the radio was working, but the interior lights once again weren't working. I checked the 7.5 amp fuse for the interior lighting. Fuse was broken again. I repeated this process three more times and each of the new replacement 7.5 amp fuses would work once and then would break.

What's wrong?

Also, I have a general question. Since my car's been at around 100,000 miles or so. Whereever I drive, whether it's 1 or 100 miles, when I stop driving and turn off the ignition, about 20 seconds later, the car suddenly revs up and sounds as if it is still on. What does that indicate? What should I do to have the car just stay quiet once I turn off the ignition?