Backup queries

Hi all backup experts of Norton community! Smiley face
Greetings of the day to all…

3 weeks ago, I started my hands on the backup (pretty newbie in this area wrt Norton) feature of NSBU. But today only I started to explore it well. So is my doubts:
1) What is the actuall use of the context menu options ‘Add to Backup’ and ‘Exclude from Backup’? I get both options clickable eventhough I havent added it to any backup set / removed it.
2) Certain files (they are located in the ‘programdata’ folder, as I was exploring that folder for some other purposes) have a badge with a grey background with a '' on it. I found it denotes that the file is excluded from backup where as a blue badge with ‘>>’ currently added to backup.
How can I remove this grey badge for the files I manually excluded from backup (by rightclicking on the target file)? Why does this badge appear on files which I encountered in programdata folder (which is related to my laptop driver programs and I accessed it today for first time after installing NSBU)?
FWIW: I clicked on the .exe files and found a new tab ‘backup’ in properties option. The backup tab listed my one and only backup set ‘contacts’ but mentioned its last backed up date not yet done [which is wrong, I performed the backup last day, also deleted ‘default backup’])

3) I am backing up to cloud, will I be able to keep multiple versions of the ‘contacts’ such that I can retrieve an older backup when needed? Or the backup deletes current backup file and adds the backup or just modifies it to add new info like syncing?

Lastly, any good steps to be taken?