Yes, mmirG put me on to it with a link, but checking on my printer, it’s easier than that (it (EDIT: ie the tutorial) was scanning using gimp), I can still use the button on my printer to do it, I just have to select to scan it to an image instead of to a file (which is what I do with documents). My camera application has cropping and straightening and that, so I didn’t have to install anything new. It’s not too difficult because I already knew how to use my printer to scan things, so not a big learning curve.
As for the covers, front and spine looks better than the whole insert together. I’m just thinking about how it looks when you download it, you don’t really want ugly text staring at you. I might do it like yours, but again, nobody else probably has my daggy old cassettes so it probably doesn’t really matter.