chasing immortality

It's a way of saying that anyone who believes he/she can achieve eternal life will fall prey to con men who will try to sell you all kinds of fakery. "Make a killing" in this connection means to make a lot of money.

and everyone knows you need two mirrors to chase immortality

Thanks, Merry Andrew and oolongteasup!
I really appreciate that.

reflects the same sentiment that Kilgore Trout exclaimed at the end of Breakfast of Champions............

"Make me young, make me young, make me young!"