1 car charger
1 charger for work
1 USB/iPhone cable for your computer
(Use the charger it comes with by your bed)
Moving a cable around all day will eventually drive you insane. Just put one in these 4 places and you'll be fine. Take your bedroom charger with you when you travel, but otherwise just leave them be.
Invstigate ways to get the phone's audio hooked up to your car. Mehtods vary depending on what car you have.
I would encourage you to not get a case for the back, but that's up to you. It's a personal preference. I don't have one, but I understand the folks who do have them.
I would actually tell you not to get a screen protector. Makes the phone worse and I don't see the need for one.
I know I'm in the minority on those last two, but I think I'm right. And if I didn't have a big ego I wouldn't be posting my opinions all over this site, now would I?