Lego heads are made with holes as a safety feature.
When Lego made their miniature head figures, they kept in mind that some kids like to put stuff inside their mouths. They decided to add holes on top of the heads so that in case a toddler accidentally gets a piece stuck in their throat, air can still pass through and the child will be able to breathe.
smarter individual would use the other hook instead of a key....
Just screw it in by hand, it isn't that difficult.
#2 not sure it would work. cars have safety glasses which prevent shattering. you can buy special purpose hammers though.
WTF? Spell much?