Hi dizzy.
Problem with writing down what you think are going to be the answers before the questions is that you have only a limited number of answers where as if you go in cold you have to look for the answer at the time. So there will be a minute taken while you look for the answer. If you would have been tongue tied and brain fogged anyway it won't matter other than you will look studious rather than lost. We all come up with the right answer long after the fact. Frustrating right.
Being assertive is about making your point. And the best way is to do it slow and clear and to not let anyone shut you down. This starts with being assertive with yourself.
Do you know the answers to the questions you will be asked? You must or why are you in this situation.
Do you have to be 100% right, would 80% or less be okay. ( Perfectionism?)
How important is it to get it right? Does it make you look bad? Do you care?
And a biggy! Are you going to like yourself less if you fail? Yes / no? Some negatives here depending how you answer.
Assertive starts with yourself.
Worrying does not help the situation once into the situation, you are there, you are stuck, make the best of it. Be assertive with yourself. Worry before the situation is different, it can be a way to prepare or it can destroy your preparation. You have to decide which it is doing. And if the latter then quit doing it.
Now this is easy for me to say because I am the type that likes a challenge and I have lots of confidence because it doesn't matter if I win or lose as long as I get in some good moves or points. Better to be remembered for one real good point than a bucket of mediocre ones. Of course this is fine if all it is is a debate not a job application. But then job applications usually call for a resume where you get to put down all the answers to all the questions they might ask. Another thing lawyers never do is put out an answer that might bring up a question they don't have an answer for.
I am certainly assertive but not competitive. I do the best I can but don't beat myself up if some one proves to be better than me. It happens.
As usual I have found your post very interesting :-)
Just babbling here, not trying to give you an answer. I know you will find it on your own, you always do.
Davit.