Upgrade SRM 5.8.1 after vcenter upgrade to 6.5

I will  upgrade SRM 5.8.1 to newest version after 2 vcenter upgrade to version 6.5

I have fiew question

1.how to make all configuration backup of the SRM?

2. Should I stop or remove SRM services before vcenter upgrade?

3. Better make on-place upgrade SRM or instal new instance?

4. If I make the on-place upgrade do I lost all configuration?

Thanks a lot