You’d be surprised. For medical info a lot of that is going to be sorted in windows servers running as either file or sql servers.

If those are important to you yes but the old desktop route generally means you’ll get access to more powerful chips plus the ability to add more storage and memory.

At a functional level I can’t see any reason why it wouldn’t work. Though my preffered method for that has always been old desktops over phones as it gives a lot more flexibility overall.

Generally speaking I find USB hubs with ports on them work pretty well with android as they’re just relying on the Linux kernel drivers for the USB support.

If the data is sensitive just give them a cheap whatever machine and have them connect to a vdi. That way the data never leaves your estate and means you don’t have to worry as much about the device being lost/stolen. If this isn’t an option I’d strongly recommend looking into an MDM solution for your devices.