Im a big fan of the Foundry's Cattery toolset for Nuke and think everyone would benefit from using them more or at least know what they can do. In this quick video I'll give you an overview of what you can expect when using some of them.
I’ve been using Midas for a little while now to do muzzle flash interactive lighting. Hit or miss like you say but man does it speed things up when it works.
In theory yes. However, I've yet to meet anyone that made it work. I read somewhere there is a big cattery update coming soon with some new models for us to use. I hope that update touches on other custom pretrained models. Keep in mind that copycat has some pretrained models which im going to assume are cattery models. You can select from the ones available inside the node and keep training from there so you could have your own "improved" one as an inference node.