Switching from the 4S to the Lumia 900.

I just switched from the 4S to the Nokia Lumia 900, and I've stumbled across some issues that I would greatly appreciate help on. First off, I can't get my iPhone 4S microsim to play with Nokia Lumia 900 microsim. Are there any special APN settings I need to deal with? Also, I can't seem to get the status bar to load correctly. Any tips for a WP7 noob?