The cover is more durable than it seems. But since its not required, best to leave off until full restoration is done. if you manage to break it, I probably have a spare.

2 - It will do this as a matter of power saving. It can also mean bad caps on the mobo.

 
5 - smell, Scrubbing Bubble cleaner. I use it to clean all my cases, the stuff is lethal yet will not damage the plastic or dull it.