Are you flying into and out of Palermo, or into Palermo and out of Catania?
I assume you are renting a car after Palermo?
Would you be willing to see Cefalu by train from Palermo? Would you be willing to skip Marsala?
Do you want to stay in Villafrati and Limina?
I would not worry about locating restaurants in Sicily right now --- you will find them easily and eat extremely well wherever you go. That should help with the overwhelmed feeling.
I don't know what your interests are, but if this trip were mine, I would fly into Palermo and spend 4 or 5 nights, visit Cefalu as a day trip from Palermo, take a train out to the airport and rent a car, drive to Villafrati and then stay in Agrigento. Then I would drive to Piazza Armerina and stay one night so that I could visit the Villa Romana mosaics first thing in the morning (I can recommend a great B&B there!). Then I would drive to Limina (long drive). If you want to spend a few days in Catania, I would be inclined to return the rental car first --- my husband was not fazed by driving in Catania, but most normal human beings would be. Fly out of Catania.
If you are wanting a town around Mount Etna so that you can visit the volcano, but want to skip Catania, we really enjoyed staying in Randazzo (1.5 hour drive to Limina, so you could visit Limina as a day trip from there).