First thing you need to do is to get the drum loose. Some WD-40 around the center cone and some banging with a hammer (do not use excessive force and only hit near center of drum) should get the drum loose. If it is stuck tight, use 2 x m8 (8mm x 1.25 thread) bolts to tighten evenly on the 2 holes you see on the drum. This would force the drum loose and allow you to take it off.
If drum seems stuck after moving out, you would need to adjust the shoe to drum clearance. Use a fine screw driver or rod to push the adjuster lever (item # 6) away from the locking position on the adjuster (item # 5) and use another screwdriver to turn the adjuster in the direction that requires lesser force.
For replacing the cylinders, the brake shoes need not be disassembled, just remove the slave cylinder with shoes intact. If you adjust the shoe to maximum, it would help when installing the cylinder.