As the title says:
Do I get webhook notification on deposits to my master address in Vault?
Can I deposit funds to the master address? What would be good use case for that?
No you don’t get notifications on your master address in Vault. You only get the notifications on your addresses.
Funding master address would be useful for cases such as an exchange that wants to always have funds available for withdrawal and you can treat it as a withdrawal account and charge it initially.