Not yet, but it’s quite commonly requested feature (as you can see here ) so I can see it making it’s way in fairly quickly.
Yes, the best way is to use or system of tools environments. You can define any tools you’d like, assign them to respective applications, or even to individual shots actually. There is a good guide for it here Ayon/Openpype Env Vars and Tools Configuration Explained and here Configuring Tool Groups in OpenPype
Not yet, but coming hopefully soon to AYON near you
There isn’t, but a great suggestion!
I’ll try to get someone else to answer the other points.