Reply to CDJ 850 vs CDJ900 Comparison help

Context:
I'm comparing the two CDJ to upgrade my setup, I have a traktor setup which I've been using for a couple of years and I've played out in a couple of clubs. I can beatmatch on vinyl and using a controller. I don't need effects really as I'm producing my own tracks at the moment. I just want a simpler setup and tear down and to be as comfortable as possible when playing live.

Questions

What is Frame Accuracy and why do I want it?, I can guess but I want a guaranteed answer, I've looked on the internet to no avail.

Are there pictures on the internet of the 900 wave display and the 850's wave display? I've seen the 800's irl and I've seen the others in youtube videos but not a direct comparison.

I've read a lot of the threads here but there doesn't really seem to be a consensus. I really can't afford the 2000's.