Astrid:
Heat a nail over a candle perhaps? I take it you are in a dorm situation.....bare essentials, huh?
Yeah, it sucks to get strange things or bad surprises in with new orchids - I once got one that, when I went to repot it, the bottom of the pot was filled with regular driveway gravel, but the seller was a small time guy that was selling from his "hobby collection" just to make a little money on the side.
Yes, foam "peanuts" or chunks are often used in the commercial greenhouses to cut costs, but then again, that is how you can afford to purchase the NOIDs so cheaply, so it is what it is.
If I buy an orchid in bloom and in pure moss, I don't really "attack" the root ball, but I will take it out of the pot, set it down in another pot and just fill in around the sides with pine bark. This allows the moss to dry out enough that I don't rot it and if there is a black mess down there I know I have to sacrifice the blooms for the sake of the plant and will get aggressive with the roots.
I would notify the sellers of the issues you have, but you will probably hear "that the only way I can sell them at any reasonable price", so it is hard to argue with that.
And I have had the same "not enough potting mix, or enough pots" scenario many times and yes, it is frustrating as it gets..... especially when you are all "primed" to re-pot. I just try to keep some on hand like milk in the fridge, but I totally understand the "exciting new orchid vs. boring old potting mix" struggle many of us go through.
Ahhhh orchids - why do we do this to ourselves?