I consider my questions brilliant and I want to reserve my rights to publish them in other forums. Am I allowed to do that or do I need permissions?
This is addressed in the terms of service:
- Subscriber Content
You agree that all Subscriber Content that You contribute to the Network is perpetually and irrevocably licensed to Stack Exchange under the Creative Commons Attribution Share Alike license.
... and it goes on for another ~600 words if you want to fully understand your rights and obligations with respect to your contributions.