For number one I’d say yes, for using real world values you can totally use the blackbody node even to this day. The node is undefeated. For it addons it will probably depend on such addons, their functionalities and options.
Two, I mostly go by artistic liberty, I don’t use real life world values much, I eyeball it if it looks good. I have an addon that lets me light my scenes with much ease and faster, it’s called Gaffer by Greg Zaal. It’s a lights manager, super useful:
https://blendermarket.com/products/gaffer-light-manager
They also have this website with useful HDRI’s:
https://polyhaven.com/hdris
Three, yes, the exposure method is useful anywhere every time all the time, when you need to control the lighting in your scene. If it’s too bright or too dark, you control your exposure to make it how you want it to look.
