Well, they had more time than that, since it would have been a huge surprise, had Germany lost against Korea.
Of course, they couldn't be 100% sure.
Yes, if you see from this angle, then yes. I just read an comment of Ralf Weber who said it would not have been possible in that given time. But anyways, why are we even talking about indoor grass? It would be much too slippery and maybe the cost play a bigger role than we are thinking.