Steven Baan no, if you arrive too early they have a desk that charges you a fee, it's the same if you arrive late in the afternoon too. They still close up shop in the evening though.
Yes you can, I did it. But you may have a valid reason to re-enter. My passport was lost by UKPA, the new passport was on its way to Thailand. The embassy gives a letter explaining the situation and you can re-enter. You are correct that you can't use it for normal travel, but you can come back on it.