I remember watching the College World Series in Omaha as a kid in the 1960s, and I remember watching Sal Bando and Rick Monday play for Arizona State. Are there any MLB players who have played on a College World Series championship team and also won a World Series ring? Of those, if any, did there happen to be anyone who played in a Little League World Series championship game?
The second half of your question is actually answered here (very bottom of page):
Did you know that only two Major League players have appeared in a Little League World Series, College World Series, and Major League World Series Series? Those players are Ed Vosberg, who participated in the Little League World Series (Tucson, Arizona, 1973, Runner-Up), College World Series (University of Arizona, Champions, 1980) and the 1997 World Series; and Jason Varitek who participated in the Little League World Series (Altamonte Springs, Florida, 1984), College World Series (Georgia Institute of Technology, Runner-Up, 1994) and both the 2004 World Series & 2007 World Series.
Vosberg is the actual answer here, his LL team played in the championship game and his college and pro teams won it all.
As far as the first half. I suspect there is far more overlap in these two data sets. I'm going to CW this and see if we can build a comprehensive list.
Roger Clemens won 1983 College World Series with the Texas Longhorns and the 1999 and 2000 MLB World Series with the Yankees.