So I've survived a couple of Ambushes which cost me 2 dwarves, a hunter and a mason (I still don't know what he was doing outside..).
I had a caravan of elves arrive when my screen went black and "a vile force of darkness has arrived!"
My dwarves were scattered all over the map collecting wood, and clothing from the ambushers, thieves and snatchers. (I didn't have a stockpile for their clothing

) I figured I was about to get slaughtered.
I issued the order, all dwarves inside. This revealed my first mistake, as the level for my bridge was outside!

I had to release the dwarves back outside, and cancel all the pending trade items which were outside, to get one of them to pull the lever. This took about 5 minutes real time. While this was going on, the two groups of attackers I saw (maybe 10 guys) were chasing a pet horse all over the map.
The order to raise the bridge (or retract it, How do you tell which you have?) was fulfilled just before the horse lost his battle with the invaders.
My fort is surrounded by a 2 tile wall, and a 2 tile moat outside of that. I've built a long and winding single tile wide tunnel, lined with traps as a side entrance. I've built fortifications atop the walls near the bridge and over by the trap tunnel entrance. I have 2 squads of 6 marksdwarves each, most of them elite.
The invaders having killed the valiant horse, and a puppy who was also somehow outside, then they entered the tunnel. After triggering 2 stonefall traps they then left.......The siege notice on top of the screen cleared and that was that. I didn't even get my squads outside before they left! I then saved.
So here are my questions:
1. Is that it? Once the siege clears from the top of the screen is it over? Or are they still lurking on the map, waiting for my guys to go outside?
2. Is there a way to designate everything inside my wall as "inside"? So when I order all dwarves inside, all I really want is them to do is get behind the wall.
3. If I'm still under siege, how will the elves leave? Being elves the are only 1 tile wide, will they be able to pass the traps and leave that way, or do I have to lower the bridge?
(FYI I use the mike mayday tileset)