Switching from the iPhone. Read the sidebar. CONFUSED!

As much as it pains me to say, I feel like Apple is going down hill. I am making the switch to Android and need MAJOR help.

I am looking at getting the new HTC One on AT&T here in a few weeks but am really concerned about how difficult it is going to be to convert my iPhone info to Android. Here are some basic questions that I hope you all can help me with:

1. I hate having my credit card connected to the app store so I use iTunes gift cards. Does the Android app store (Google Play?) have gift cards.

2. How easy/difficult will it be to transfer all my music to Android through iTunes. Will I need to plug my phone in to my laptop every time I download a song or is there an iTunes app for Android?

3. WTF is rooting? Is it jail breaking?

4. What are themes? Are they just downloadable packages to customize your app icons or widgets? What is the difference between apps and widgets?

Sorry for all the questions. I have been an iPhone user forever so I feel like a complete dumb ass when it comes to Android...