How would you handle PCs that always cast Light?

Has there been a final ruling on whether Meld in to Stone is a Self cast spell or not?

How one would go about crafting arrows of slaying?

Can the Warlock Pact of the Blade be used to create shovels, crowbars, etc?

Can a creature who is immune to bludgeoning damage fall from any height unharmed?

What’s the reasoning behind not capping Destructive Wrath?