- The Veeam server needs to be restarted to clear the lock of the logs. So a reboot is certainly advised. If I am not mistaken it is possible by simply "restarting" all the veeam services but in such cases (locks...) I prefer windows to do a full restart.
- You do not need to stop the services first. Just make the changes, but before they go into effect, the reboot
- You can leave them there and delete when you feel they are not needed anymore
- Yes for proxies/ gateway servers (but it does mean you need to use the registry ON those servers