I think your magnifying mirror will work well for me! I have tried a loupe, but not as good a one as @mulveling recommends. I will get both!
I have a USB digital microscope, but it is a pain to set up. I might also try a car inspection camera which at least includes a light source and is self-contained. I don't think it would help for cleaning, though.
Really need something I can use after each side is played, and which can stay in place
@lewm I am getting pretty quick at removing the entire tone arm from the mounting board. Much faster for me than removing and refitting a cartridge!