No. I got mine from Ollivander's. He's a wand maker.
Do they? That's curious. I guess it isn't all that different.
We can change things into other things. It's called Transfiguration. Potions are magic you can ingest. Depending on the Potion, it could have various effects. There's blood replenishing potions, Potions to make bones grow back, potions for dreamless sleep.