my character keeps losing health with no explanation, any ideas why this might be happening?
Assuming this is multiplayer: you’re being attacked by an enemy but because of lag or bugs you can’t see that enemy. The host will see it, though.
I want to start making custom weapons, is there anywhere I can get the item codes to to put in the weapon creator for the combination?
Yes, there’s a wiki page listing all of them: https://tgp-official.fandom.com/wiki/Item_Codes
Will the player receive fall damage when jumping off the pillar your house is on and/or just in general?
Yes. It lets you skip the part where you build up to your gates which isn’t ideal.