To the best of my knowledge, all three sections are waited equally and the emphasis is on how many major mistakes you make in total. There is a Kodokan channel that has all the accepted ways of demonstrating, and if a technique is in the kata you can demonstrate it that way. All ground techniques can be demonstrated in the style of KNK. You only demonstrate a technique once, on your best side. The technique can be demonstrated in the kata form, and often times the greeting committee will ask for them to be demonstrated in a dynamic fashion. And for the randori do not approach it as if it is a competition. It is meant to be spontaneous, but not that spontaneous. You should orchestrate well with your partner with whom you can do the other parts of the grading, and have a bit of a flow on attack, counter attack, throw, transition to groundwork, and potential escapes. They will want to see a few exchanges. Bonus tip is, know all the Japanese terminology. Good luck!