Noch: that would mean getting within 30 ft. At the moment you are around 120 ft away. There is little if any cover between your position and the guards' post, though your Hide/Move Silently may just be high enough to get close enough
Why of course you do you're all alert so you all gain a surprise round... i should ahve said that in the initiative post. And I have already been doing Listen checks for the enemies, though for now, since i assume you are not directly under the door and whispering, they have been difficult. Casting a spell right near the door would be a slightly different matter