View 3d files: If my memory serves me correctly, you just double click a 3d file within the Solution Explorer, same as with png images or txt files, they also open on a seperate tab. -I dont know about animation though, as my animations were done through code, in-game.
For your own framework… I wouldnt know where to start besides online archives, tutorials, and asking people who have themselves made a framework.
-There hasn’t been one thing I have imagined, but couldn’t do with mono-game, so I dont even know why anyone would do something like that 
If you are actually talking about libraries, to save time coding, that seems more manageable, and there already some good ones out there, I gather. Monogame extended has its own section on the forums. -Again, I dont use anything besides monogame vanilla… When I need the same method or class in different projects, I just copy paste them. Its not usually more than a handfull…
Collision is no problem, because there so many ways to do it, you can just make up whatever you want… Even a mouse click in the menu is collision detection, so you will probably learn collision detection in your first monogame tutorial.
-Networking is something I know nothing about, other than my own thoughts:
There are so many things to do with connections, you would need to know what you are looking for, before you start to build it…
I guess you could easily write some code to ping some things, if you want to do have an immediate impact on your surroundings. -But something like a high score server for your game potentially entails all sorts of hardware choices, maybe even bills, etc…