Code of P1457

I recently purchased this car. A couple of days after, the check engine light came on. I immediately went to Advance Auto to get the code. I was given a code of P1457, and was told it had to do with the vacuum lines or hose, but would not affect gas mileage or performance. I was able to drive it for about a week like this. The day I had the oil change and tires rotated, I noticed that the wipers were moving slowly(which I thought was the wipers motor going bad. It's 16 years old, after all!). But then the radio became static and then stopped working. I turned it off and got some shopping done. Had no problem starting the car. On the way home, the radio again became static so I turned it off and then the LED display started to blink on and off. On the highway I noticed that my fuel gauge had gone to E and the speedometer went to zero. I decided to go back to the gas station just in case the tank really was empty. As I drove the car it began to sound like it was out of gas. And then it stopped running. I tried restarting it only for it to sound like it wanted to start and then it became a fast click.
I bought a new battery which helped momentarily. Took it to AutoZone to get the alternator tested, and was told it needed to be replaced. So, new alternator is on. However, the alternator is not charging the battery while driving. Two mechanics have said that there is an inline fuse behind the positive battery terminal. No one can find it. Is there a diagram of the engine showing where this fuse is located? And what the amperage of it is supposed to be?