"I'll keep researching.."

Are you not satisfied with the info provide here? What additional info are you looking for?

Philadelphia airport is worse than Frankfurt airport, but you'll do fine in both airports. Just don't get too stressed.

check your bag through to your final destination in Italy.

Deplane in Frankfurt, follow the signs - in some airports there are separate signs for "Transit Passengers", so follow those signs.

Going through Immigration and Customs is like going through the checkout at a grocery store. Just make sure you have your papers handy.

Once you are allowed into Germany, go through and find your departure gate just like you would in the US. No big deal, as someone has already written, the signs are also in English.

Have a fine trip! Italy's a great country!

I don't know what additional info I'm looking for I just want to make sure that I know what I'm doing and how to do it. All this is very very helpful I just want to be extra prepared!

If you know what you're doing and how to do it you're taking all the fun and adventure out of travel. Some of my favorite travel memories are of doing it wrong and bumbling through without a clue. Getting lost and seeing some of the most wonderful sights and having a great time.

You're going to have to accept you will never know everything about where you're going and learn to relax. Maybe you'll discover this on your own.

Well I don't really feel like getting lost all by myself in a foreign country and missing my flight. I just want a general plan of how things are going to work so I'm less stressed out...

You won't get lost in the airport, relax and enjoy your trip.

"I rechecked my itinerary and it's BMI operated by Lufthansa."

"Operated by Lufthansa" is the key information -- it is a codeshare flight (ticket sold by one airline as if it operated the flight, but actual travel is on the equipment of another airline), so be sure you know the Lufthansa flight number as well. You are going to be looking for a Lufthansa gate, not a BMI gate.