Normal desktop monitor viewing distance (at the back of an 80cm deep desk), but I'm going to use it at 1x scaling. 65" will probably make the text too small -- I think the ideal resolution would be an ~80" display, but 75" and 85" TVs would be wider than my desk.
Might take about 10 minutes to migrate your mouse from one corner to the other!
The mouse will have offspring and die before reaching the other side.
This is an interesting idea. You should write a blog post or something about your experience once you've settled in.