Based on the clue '54 68 ad presided during a big barbecue', what is the answer?

What is associated with: 52 people leaving this country january 20 1981 made world headlines? Based on the clue '524 firms competed to design a new library at this...', what is the answer? What is associated with: 525600 minutes how do you measure measure a year? Based on the clue '53 years before the trail of tears this tribe sign...', what is the answer? What is referred to by '55 25 5'? What is referred to by '550 spyder boxster 944'? What is associated with: 56 in 1997 with the seattle mariners? Based on the clue '56 jackstraws no 56 spillikins no 56 this yeah tha...', what is the answer?