1) Is black seed oil sunnah to use and if so what does it do and what other oils and or natural remedies are sunnah and what are their purposes

2) I’ve also heard that oiling your hair is sunnah too?

by

1) Yes it is recommended. You may read here about that:

https://www.al-islam.org/islamic-medical-wisdom-tibb-al-aimma/oil-violets

Check the table of contents for other oils.

2) Yes it is