457b RMD

I am subject to RMD. I understand that I can aggregate RMDs from my different IRA accounts but I must calculate and take the RMD from the 457b separately from the IRA RMDs.

I am moving my 457b to a new manager. It will be converted (rolled over?) to an IRA (not Roth). Do I need to take the 2022 RMD from the 457b before moving the money?

If not, must I still calculate and take the RMD from the roll-over IRA rather than aggregating them my other IRAs.