You can replace just the calipers. If you want to re-use the hoses, your options are any post-mount Shimano calipers with an in-line style caliper hose connection.
If the hoses were the minimum acceptable length now, you may need to replace them anyway since pairing the old barb and olive with a new, different brake doesn't always work and isn't how the system is designed to work, because the olives conform in place as they're tightened and putting them in new calipers can result in leaks (doesn't always but can). It's better to trim the end and start fresh even if you're reusing the hose.
There is no getting around the need to bleed the new systems and yes you'll use Shimano mineral oil or another compatible one.