How Many Different Players Appeared on Kellogg's Cards?

From 1970 - 1983 and from 1991-93 there were about 900 different Kellogg's Baseball cards produced, depending on how you count variations.  I have four questions relating to that.

1.  How many different players were pictured on the cards?  This includes the 1972 All-Time Greats Set and the 1991-92 All-Star sets.

2.  Of the players included, what percentage of the players only appeared on one card?

3.  Which Hall of Famers appeared least often (twice) - excluding the All-Star sets and the All Tine Greats set?  I counted at least six players who match this.

4.  Which likely future Hall of Famers appeared only once - again excluding the All-Star sets and the All Tine Greats set?