I can't even get the phone to act as a drive to allot a fixed drive letter to. A prerequisite, it seems.
Correct. Early Android versions appeared in Windows as a drive, with letter, so you could do all those things. But with 4.4 Kitkat (I think), Google made phones "Media Players" or something like that, so they no longer appeared as a drive. This was a nuisance if you wanted to do what you are trying. The good thing is that you no longer have to enable "USB storage" on your phone to get access through Windows; now you just plug it in and do as Gouli says.
If I want to regularly transfer stuff eg photos back to my computer, I use SyncMe (Lime green icon). You can set up wireless transfers: you can do all the types of syncing (one-way, mirror, update both sides).