M. B. Downey
Will the player with the courtesan guild get the ability and later on also the victory points the leader generates?
Just the ability. Nothing changes, as I said above.
Will you be able to copy a mummified leader with the guild in the first place? (Thematically I'd say no: it's a nasty picture... Courting a dead person... On the other hand: wasn't it the custom in ancient Egypt to be buried alive with your 'master' when he/she died?)
No. The leader is no longer there to be copied.