The drums are inboard which means the entire hub will have to be removed. If you don't have a wheel dolly, I would recommend removing the tires and wheels. To remove the axle, you will have to get something threaded into the threads which you describe as poor. You can probably chase them with a bottom tap and they will be ok. Then use a slide hammer to remove the axle. Once you have the axle remove the axle, this will expose a lock nut, a lock and an inner nut. These need to be removed.. preferably with the correct sized socket. Back the brakes off as far as they go and you will be able to remove the hub and drum in one piece. The drums are bolted to the hubs. The whole thing is quite a lot of hard work. This is why the trucking industry switched to outboard drums about 25 years ago.