How many copies does Windows server backup keep for backup to local volume in Server 2019

Good day all,

So I've Windows server 2019 Datacenter 1809 running. Also have Windows server backup installed on this same server. I have configured scheduled backup on this server through WSB to take system state backup few times in a day. It's using VSS Copy Backup. It stores backup to separate local volume. Now following are the things that I am trying to find further.

A) How many copies will WSB keep on ongoing basis? There is no option of mention how many copies you want to keep in WBS wizard. I guess it's not granular enough.

B) Will my drive run out of disk space?

C) It's currently using up nearly 22GB of space. So does WSB take first backup as full backup and following ones are delta? So when you do restore it needs first full copy and latest delta? Is that how it works?

D) One more good thing to know is Performance. How does running Windows Server Backup impact on server performance. I am noticing that when backup is running CPU and Memory usage spikes. I believe this is also partly due to anti virus tool on the server. Will excluding WSB process wbengine.exe from AV scan help with performance?

I've looked up number of articles online like below but there's not much information on how many copies it will keep by default for such backup operation on server 2019. And whether it will run out of disk space at some point? Or how good is it at overwriting previous backups so preventing filling up of disk.

https://techcommunity.microsoft.com/t5/storage-at-microsoft/backup-version-and-space-management-in-windows-server-backup/ba-p/423891

https://backupeverything.co.uk/a-step-by-step-guide-on-how-to-perform-windows-server-backup/

It's pretty hard to find out this basic information anywhere despite having so many articles about WSB all over the Internet...