Well, first of all, welcome to CrossfireForum.

Most shops do overfill the oil, as the manual instructs a fill of 8.5 quarts where an even 8 quarts seems better, I've been doing 8 quarts for all three cars since 2009.

I do not know what 'back panel' you are talking about. The overflow drain hose from the filler area dangles from under the car and overflow drips on the ground. When my car smelled like gas from time to time, I found gas seeping from the seam between the two halves of the fuel pump so I replaced the fuel pump.