crushes are harmless.There's nothing wrong with crushing on someone older 또는 younger...up to a certain age.I think up to 10 yrs older than 당신 should be old enough though.
It's a crush, there is no age limit. When I was a teenager I had crushes on older men, but there was no harm in it cause nothing would never have come of it.
Of course not! I had a crush on someone who was in 11th/12th grade while I was in 8th/9th grade. Plenty of people have also crushed on celebrities, and even had 더 많이 than one crush. (Which applies to me as well) It's totally normal, there isn't anything to worry about ^_^