[IROC]

I think the ear popping thing is someone pulling your leg. Opening windows doesn't make any difference either. The pressure differentials are really not that great.

The problem with roofs is that alot of times they are not really attached to the house other than a few toenailed nails. They fly off all the time around here. I've even heard people talk about them lifting up a few feet and setting right back down again.

Mostly - from what I've experienced personally - the only warning you get is the classic "freight train" noise of the massive amount of wind (that and stuff flying through the air). Around here, they call it being "weather aware", but mostly just keep your eyes peeled and take cover as soon as you see something. If the tornado is big enough, it really doesn't matter what you do, it's going to get you.