1) What is ACES Colour space? I know that 3ds Max + Corona cannot natively work in it but it can be applied in Post through the VFB but I typically play with the value until I get a satisfying result, depending on the image. Do real-life photographers work in ACES?
That value in the Corona VFB is just a tone mapping curve. 3dsmax + Vray can use ACES. No Photographers don't use ACES (mostly), if you work in Broadcast then you would have probably had to use it at one point or another. If you would like to understand what ACES is I recommend this article:
https://chrisbrejon.com/cg-cinematography/chapter-1-5-academy-color-encoding-system-aces/2) Is it better to work with Photographic exposure turned on? I find it produces more "boring" results compared to it being turned off, less punchy images etc.
Depends, if you are matching a photo 1:1 then its easier to follow the setup of the camera used to take the 'backplate'. Otherwise its just personal choice.
3) What is the difference between Highlight compression, Filmic tone mapping, Tone Curve etc?
Highlight compression is simply just compressing highlights/burnout.
Tone Curves are just basically Curves like in Photoshop - left side is darkest shadows (blacks), middle is midpoint, right side is brightest highlights (whites), adjust to suit.
Tone mapping is just controlling the dynamic range in the image to suit whatever it is you are trying to achieve. There's plenty of different methods, an LUT is basically a preset of a tone map, same with Filmic, its just a term that was used to mimic traditional film photography but can look different in different scenarios or render engines. There's more to it then that but its about as basic as I can put it.