You don’t need to answer every question. You don’t need to know every fact. You don’t need to have absorbed every detail about your examiners.
To be alright in the viva, you don’t need to get everything all right in advance of it. You don’t need to respond in the right way for every question. Of course, do your best! Of course, try and work hard! But if your mind goes blank, or your freeze, or you forget, you will still be alright.
You will have done enough before the viva and will do enough during the viva to pass.
You’ll be alright.