All good advice so far. No, the screws do not have to come out, but if the drums are stuck to the shoes removing the screws makes life easier. Heat, PB Blaster or Kroil, and an impact driver (uses a screw bit and gets hit with a hammer) all help. Iirc, for replacements you can use a flathead socket cap screw. When you reassemble, you will need to make a thin paper gasket to go between the drum and the hub. And putting the hub on the differential separate from the drum is far easier.
