What is referred to by '30'?

Based on the clue '30 years ago she was mary stone on the donna reed ...', what is the answer? What is associated with: 30 years ago this singers 1st tv special won 5 emmys in 1995 her hbo special did the same? Based on the clue '30 years before blair witch this hopper fonda bike...', what is the answer? Based on the clue '30 years older this composer was a pal of vladimir...', what is the answer? Based on the clue '300 spartans led by leonidas held off persian troo...', what is the answer? What is associated with: 3000 above sea level a famous parkway extends 450 miles in this virginia north carolina range? What is associated with: 3000 will buy a 6 oz baccarat flask of mens perfume from this iranian born american designer? What is associated with: 300000 square mile plain thats home to the argentinian gaucho?