spindle nut issues...

the drum is just stuck. they're always stuck! if its REALLY REALLY stuck a trick that should work on even the worst is to drill into the area where the drum meets the hub (the 2" or so circle). you only have to drill in 1/8", which nicks the circle, relieving tension and substantially providing a place for penetrating oil to enter. doing this doesn't harm the hub nor weaken the drum.

leave the hub on the axle unless you're changing axle bearings or the backing plate. i've rented pullers etc to do it, but for the last decade i just take the nut off, pull the axle with backing plate etc sandwiched on, and take the mess to a machine shop and have them press the hub and old bearing off, the new one on. then reinstall the hub at home.

don't even bother to remove the cotter pin; it'll shear at about 20 ft-lbs. it's not there to maintain torque. it doesn't really have much of a function in fact; though if the nut came loose where it could spin off, likely the press-fit would not be affected and if it was, the nut won't be involved any more!