[@savannahssu]

Well... That is a lot of questions lol. I'll do my best to answer without prattling on though. Here we go. 

1. It's actually the latter. A medium can be any inanimate object, but of course if one just picks up a stick, don't think of trying to cast any amazingly powerful spells with it. It's just a stick, after all. 

2. Spells are one time use, but it's the gathering of energies that wears down a medium. The user is gathering magical energy proportionate to the type and scale of spell and channeling it into the medium itself. As I said before, a stick wouldn't be able to create some kind of meteor shower because it would break and the spell would fail. However, a medium can break even if a spell is successful due to the strain a large mass of magical energy comes with. There's nothing to recharge. Magical energy exists in the atmosphere of the world, one just has to learn to gather it into a medium and then learn spells to cast. 

3. Definitively no. This isn't anything close to a stat-based RP even where magic is concerned.

4. No. A stick will always just be a stick and it will never be able to handle large-scale spells--tis life. The thing about these spells are that not everyone just walks around being to summon a firestorm either. One has to learn how to conjure magical energies, focus it into a medium and separately learn each and every spell they want to cast. Considering the fatal cost of magic and people's general laziness, there aren't going to be many walking around with the knowledge to cast firestorms and cat-7 earthquakes and the like. However, I'll go into more detail on that when we have a defined cast. 

5. If a human casts a spell without a medium (aka channeling the energy through their body) they develop the disease which shuts down vital organs one by one. It's not instant death, but it's much more than weakened. Imagine a lung just ceasing to function completely and then every few days something else follows. That character would have a very agonizing final living. 

I hope this helps you and everyone else.