There have never been five past winners in a category. But there were a few times with past and future winners nominated together:
1967 Best Actor- future winners include Warren Beatty, who won for direction
1968 Best Actress
1973 Best Actor- future winners include Robert Redford, who won for direction
1985 Best Actress
1990 Best Actress
2001 Best Actress & Best Supporting Actress
2002 Best Actor (four past winnners, and the fifth nominee won)
2006 Best Actress
Italy has the most Academy Awards for Best Foreign Language Film. 13 films from Italy have won this award. In total, 27 have been nominated.
Yes. They were the winners of the Best Action/Adventure Game category and was nominated for 7 others, including Game of the Year (they lost to Mass Effect 2).
No. She has never even been nominated.
No such comprehensive list exists.
The final Category on October 2 2009 is Emmy Winners
Best Actress
The Final Category for January 13 2010 was Record of the Year Grammy WinnersRecord of the year Grammy winners
In theory, the size of the role. Main role- lead, small role- supporting. But there have been cases of "category fraud", someone having a big role in a movie (even the biggest), and being nominated for supporting- like Ethan Hawk in Training Day(2001), and two winners Timothy Hutton for Ordinary People(1980) and Benicio Del Toro for Traffic (2001), for example.
The cast of Unlucky Winners - 2014 includes: Craig Knitt as Jimmer
The cast of Soul Winners - 2011 includes: Tim Ormond as himself
The cast of Winners - 1978 includes: Dick Gjonola Bob Purvey as Flip
The cast of Blue Winners - 1945 includes: Ted Husing as Narrator