If I go to the Apple Store tomorrow or this weekend, will I be able to get into the store without having to wait in the long iPhone line if I only want to buy a case?
You should be able to walk right in after speaking to someone stationed at the door who'll make sure you aren't mistakenly hoping to get a phone, but it'll kind of be like going to Best Buy on Black Friday to pick up some blank DVDs.
I'll be going tomorrow morning to get a leather case and AppleCare+. The rep I spoke to today said I could get AppleCare+ without the phone as long as I had the serial number.
Actually this is super easy to do. Last two years I got my phone via Best Buy pre-order, but they didn't get the official cases. Just went to an Apple Store, walked past the line, and told the staffer by the door I was just going in to buy an accessory and not a phone. They said no problem go right in.