Migrating desktops computer in a migration session

Hello,

I am being asked to migrate 100 000 desktops and preserve group membership.

I read an KB 24748 that the only way to preserve group membership is to pre-migrate computers objects in a migration session and make a move with RUM afterwards.

What is the best pratices in terms of session properties ?

1. How my import file should look like ? I read that it should be : sAMAccountName sAMAccountName cn name
2. Should I add the sidhistory ?
3. Should I set the UPN to the target domain ?
4. Should I copy the account password ?

Thanks