They probably want to clarify and make sure of the following based on the documents requested for;
That the company you worked for exist
That you actually worked in this company
That you also performed the duties you claimed you performed.
So questions will come in any form relating to these.
You also need to be able to explain to a dummy what you do in the company and for how long, in relation to your reference letter and NOC. Get used to questions like dates when you started working there, who your supervisor is (probably), who your CEO is? lol...(okay, this is not funny but we don't know the extent to which they might ask questions.
In all, be confident.
Look straight into the eyes of the interviewer when answering the questions.
Also pray for God's guidance.
Wish you all the best!
I understand they usually issue visa/COPR on same day. Even if they don't issue it same day, you are very close to getting your visa.