Before the Muppets became famous, Kermit was a common name. I have read that Jim Henson did have a friend named Kermit, but some sources have said that Kermit The Frog wasn't named after Jims friend while other sources say that he was named after a childhood friend.
Oh, and Kermit The Frog wasn't named after Kermit Love, in case you are wondering.
As for muppet refferences, I have read that in one of Traveling Matts post card segments, he went to a drive-in that was playing The Dark Crystal, and I remember seeing a Grover doll in the background of a bedroom in Uncle Matts Discovery.