Machine Policies and Automatically deleting of old machines

Question 1

Background: Application and device control being used to restrict USB and External devices. Level of access seperated by groups in the SEPM.
Machine Naming standard is location followed by serial number as to why mahcines are reimaged with the same previos name.

Problem: Machines being reimaged (same hardware) with the same machine name are not going to the default group where the image is set for but the previous group where they were in.. This is an issue becuase by default any machine being imaged should be completely locked down.

Solution ?

Question 2.

How can machines have a lockdown policy applied before being autmatically removed from the SEPM. Auto removal set for 30 days.