Replace Shimano MT500 Caliper I'm not finding a huge amount of information online about doing a caliper (only) replacement. My rear Shimano MT500 is having issues and I urgently need to get it working, therefore I've purchased a brand new caliper of the same model.

I can't seem to find information on best practices on how to do it though. 

Should this be as straight forward as draining (?) the oil from the brake system, unscrew the rear caliper from the hose, attach new caliper to the hose and run Shimano oil through the system/bleed? 

Are there any gotchas to look out for? Can I expect the unscrewing the hose/attaching the hose to be a simple process?
Normally when you disconnect a brake hose (eg to install a new caliper), you are well advised to replace the 'olive' with a fresh one to ensure a quality seal. Shortening the hose also needs a new connector insert but you don't say you're doing that in the question.

I would treat this as an installation of a brake and follow the relevant steps in the dealer's manual, noting that Shimano states that "This dealer's manual is intended primarily for use by professional bicycle mechanics."

You shouldn't lose much fluid out of the hose if you disconnect only one end at a time and don't squeeze the lever, then I would give it a bleed as per manufacturer's instructions to remove any air. I don't know if the new caliper came with any fluid in, but by doing a full install and bleed it will fill up and purge any air you might introduce.