Can a role be granted roles+privileges in oracle all at the same time?
Yes, you can grant as many roles or privileges to a role as you want.
The order or priority does not matter because a role or privilege always permit something. Unlike for example Windows file permissions you don't have "allow write" and "forbid write" - where the priority/precedence matters.

Either the role gets a privilege or he does not.

However, you can create ROLES as use the ROLE as marker in PL/SQL at DBMS_SESSION.IS_ROLE_ENABLED(...), there is would be possible to "restrict by granting" and the order and priority could matter. But such design would be quite ugly and is not recommended.