It appears you are launching the server by just double clicking the jar file. This starts the server with only 256 MB of ram, which isn't enough to do anything in newer versions of the game.
Horse armor isn't able to be enchanted in survival not even thru books. i believe this is b/c it is considered Misc. instead a Armor/Weapons and is not enchantable otherwise.
Now eating fills 2x the intended amount! not bad but not an intended feature accourding to the wiki stating half of what is givin
It's a complicated thing to explain in it's entirety, but this is an example of the piston's quasi connectivity. It's something that has been in the game for quite a while now.