yes
In 1985 Villanova won a national championship as an 8 seed beating Georgetown the highest seed ever to win a national championship
George Mason 2006 LSU 1986
Yes, quite often. The most recent was LSU in 2006. Arizona won the title as a #4 seed in 1997.
A 16 seed has never defeated a 1 seed, which is their first opponent of the round of 64
Highest seed would be a #1 seed, of course, done many times.
George Mason was the 11th seed in 2006 and made it all the way to the Final Four. I don't know if that's the lowest seeded team to make it to the Elite Eight or Final Four though.http://a.espncdn.com/ncaatourney/brackets/2006Bracket.pdf
The lowest seeded team to make it all the way to the Final Four in the NCAA basketball tournament was an 11 seed and it happened four times:11 seeded LSU in 198611 seeded George Mason in 200611 seeded VCU in 201111 seeded Wichita State in 2013
11
Michigan State is the number 2 seed.
There have been three times in NCAA Men's Basketball history that no #1 seed has been in the Final Four. The only three years were 1980, 2006, and 2011 with the following teams included in their separate final fours: 1980: Louisville (#2 seed), Iowa (#5 seed), Purdue (#6 seed), and UCLA (#8 seed) 2006: UCLA (#2 seed), Florida (#3 seed), LSU (#4 seed), and George Mason (#11 seed) 2011: Butler (#8 seed), UConn (#3 seed), VCU (#11 seed), and Kentucky (#4 seed)
Since the 64 team structure, Virginia made it to the final 4 in 1984 as a number 7 seed.
They were an 11 seed.