Have you considered making armor/weapons/tools etc completely disappear if the player lets the durability get to zero?
No, no plans for that, I do want to add a Diablo 2 like HUD overlay indicating that one of your armor pieces is about to break or is broken.
Also, is there a way to transfer liquids between glass jars and plastic bottles yet?
Nice that you brought it up, technically currently there is by using a blue barrel block, pouring water in it, then taking it out with a different vessel, but I'll add a conversion recipe, I wanted to, but I forgot.
And would it be possible to add a slider or number field to select the quantity of item to split from a stack? I am thinking something like how the game Rust does stack splitting.
I have plans to some day add custom right click context menu when interacting with items in inventory etc, but regarding slider, not sure.