I'm updating the MA1W to MA5D-12xxx. If I reuse my existing MA1W socket for the MA5D-12, will the terminal arrangement still be correct?

Not necessarily. The socket itself can be reused, but the terminal arrangement may differ depending on the specifications.
Check the switch on the back of the MA1W to determine whether power is supplied to the transmitter.
If the switch for supply of power to the transmitter is ON, use the MA5D-12x.
If the switch is OFF, use the MA5D-02x.
As the power supply specifications differ, make sure you select the appropriate one.