I made some minimal tweaks in here that should serve as examples.
I screenshotted the project browser where you should look to see my changes (see attached image)
https://www.dropbox.com/s/n3hj792vzzbfc8i/Sample%20Project.rvt?dl=0As far as a written description of the things that I think will assist you, I'm more interested in informing you of things that will help you make more informed searches, and more informed decisions about what's relevant to what you're trying to do.
Prior to Revit 2015, Revit had mechanical components of all kinds, but they were not compatible with Autodesk Fabrication whatsoever. They were independent of that platform. Autodesk later made the decision to start making it possible to use your Fabrication ITMs and libraries in Revit, and thus began building "Fabrication Parts" which are significantly different from the ducts, pipes, and fittings that were native to Revit at the time.
So, after 2015, you had two types of each MEP content type. The "design" revit families which include duct, pipe, duct fittings, pipe fittings, etc. And then you have the detail level Fabrication parts. In 2016 they were categorized as Fabrication Parts, in 2018 they are further broken out to MEP Fabrication Ductwork, MEP Fabrication Pipework, etc.
This is important because when creating a schedule for your assembly (spool), you understand that a schedule for "pipe" is a schedule for design pipe. Not fabrication pipe. And if you drew with MEP Fabrication Pipework, your schedule is not going to show anything. But an MEP Fab Pipework schedule will. Make sense?
On the subject of using assemblies. Each assembly should define one spool. When making your next spool, you are thereby making a new assembly, and the sheets and views will be under that one. In the project browser, try right clicking the assembly itself and use the "Create Assembly Views" dialog. This suckerfish is quite nice. Everything it spits out will not clutter your project views/sheets/schedules at all. They will be contained within the assembly itself. The schedules will not even need to filter for the assembly name.
Anyway, I hope that helps kick things off. Again, I understand how frustrating it is to try to get started in Revit because the information often contradicts itself. The better you know the history of the product, the easier it starts to get (if what you're reading is timestamped). Cheers.