Luke didn't knock him into the Sarlaac pit, Han did. We don't know how old he looked as he always had his helmet on. And it's been 5 years since ROTJ.
I never liked the look of the Slave 1 (or the name, to tell you the truth). OTOH....when I first went to see "Star Wars" (as it was known back then) on the first day it opened, I was having some problems with Luke right off the bat. He was trying to weasel out of a deal with his uncle, to go to the Imperial academy even though he knew about the Rebellion (and one of his friends had gone to fight with the Rebellion); he lied about a task