Help With Randomizing

First off, I'm new at (programming) excel. However I've used the program for years now. Here's what I wanted to tackle for my first project:

1. I've made a spreadsheet that looks like a bracket system (think NCAA tournament kinda thing, loser stays behind and the winner progresses on).

2. I'd like to make a formula where each time the file is loaded, or at the press of a button, each of the starting brackets are randomly filled in from a pool of objects. What I want it to be is a "choice" tournament, where you are asked to choose between "A" or "B" in each stage of the bracket.

3. If that is clear enough, I'd also like to track stats, ie: popularity % of each object is chosen, etc.

Any help would be appreciated, and I hope this is posted in the right spot. Thanks in advance.