BO4 - Backing up server configuration best practiceandaffect of sp updates

Hi,

Using BO4 SP5 and have made some configuration changes to the services (e.g.extra webi processing servers)

Have a couple of questions

1) What is best practice to backup these changes. Is it using the central configuration manager option

2) When apply service pack updates are changes done overwritten e.g. if create extra services, split aps or tewak memory parameters are these overwritten when apply sp update.

Thanks