Will I receive a certificate after I pass the theoretical exam?

For the new exam under the European regulations:

Yes, for A1/A3 you will receive a proof of competency which you can download on "My page" at flydrone.no.

There will also be a certificate for A2 once this is implemented in the new registration system.

For the old exam for RO2/RO3:

No, you won’t receive a separate certificate, but you will receive verification that you have passed the exam. 

The old exam is not valid for flying under the new European regulations.