You can get a mushroom cloud from enough high explosive. I've seen mushroom clouds from the 10,000 lb bombs they used to clear LZs in Vietnam. IIRC the cloud is caused by air rushing back to the vacuum caused by the explosion.
If you shoot major matches, use brass cased. Not because the cheaper stuff won't work, but because the safety officers in the pit volunteered to run the match for you to shoot (and often spent their own money on a hotel for a night or two) and they get only the brass as reward.
Don't be a cheap bastard - at least leave brass cases behind at a match.
You can - but depending on the lighting you may not see much.
You can also wear sunglasses in a night club, if you really want to.
Seriously though, Oakley do make a range of safety glasses suitable for shooting - but not all their models are rated for that so check the specific pair you want to wear. They are available in a range of tints from clear, through to dark suitable for use in the sunshine.