1. Sure regexp works, but you will have to delete one of the 50 for it to show up. First come first serve kind of thing. Specially annoying if you start to split a BT into two BT's the old one would still "take place" until controller cleanup job run...
For .NET core (I mean without framework) you have to include the agent in the build process of your application. Ther's no "real" installation task. As for the upgrade process it's pretty straight forward. Just chose upgrade. all of AppD's agents can...