What has to be performed first?
Should the resources first be processed and then computers migrated?
Can computers be moved to target domain and then the resources processed?
There is no rule or sequence when processing resources and migrating computers. Resources can be processed on any machine, independently whether the computer is in source or in target domain, resources can be processed even if the machine belongs to a work group or another domain.
However Quest recommends to process resources first and then move (migrate) the computer.
User Guide for QMM provides a good explanation.
"Moving End-user Workstations and Servers"
Moving end-user workstation to the target domain makes up the user switch. After a computer is moved to the target domain using Resource Updating Manager, the last logged-in domain name is changed to the target domain name, so the user logs on to the target domain and starts working with the target account.
You should always make sure that user profiles were processed prior to moving their workstations to the target domain. If you selected the Change last logged-in domain to the target domain option when moving computer accounts, the default logon name will be changed to the target domain name on each computer that has been moved. If user names were not changed during the migration, users will probably not notice the change and log on to the target domain. If their profiles were not updated yet, they will get new profiles.