Watch Palpatine's over dramatic pleas for mercy and his eyes shifting as Anakin and Mace are arguing. That will settle any argument as to whether Mace beat Palpatine. Based on Palpatine's mannerisms and actions during that scene, it's pretty obvious he let Mace beat him.
Exactly.
If Palpatine would have murdered Mace, it would have given Anakin the opportunity to attack Samuel Jackson and bring him into the dark side.
God.