I think we must assume the answers to both questions are "yes". The whole demand for a correction hinges upon it.
Some devs and players/dm's don't like it others do. It's NOT a true/false question. It's not a universal truth. SO there will NEVER be an agreement on this IMO. I know I can't see a situation where I'm going to change my mind on it. CLW isn't bad and it's not an exploit as far as I'm concerned.
You don't have to confirm crits anymore but the wording of vorpal suggests not only does it only happen on nat 20 but that if the nat 20 does not put you 10 above succeeding then it won't activate.
So with the wording from the staff you can sacrifice any spell slot of the same level to cast a spell in the staff. Does this mean a wizard can use this staff to heal even though they wouldn't usually be able to cast the spell?
You don't need to build around avoiding AOOs anymore because people get a max of 1 per turn so strength monk will be fine. Aoo uses your 1 reaction for the turn so at worse you get hit once add you retreat