1. I know that some older PowerBooks left keyboard marks on the screen after a while, but I'm not sure if that still applies to recent one's. It's one of the downsides of the very slim design.

2. You can't. The PowerBooks use the keyboard for cooling, and there's a high risk of overheating when running it with a closed lid. That's why it always goes to sleep when closing the lid.

3. Your network administrator should be able to give you the necessary information you'll need to setup your network connection.