You could always save the game right after the "Strike The Earth" and force quit if things don't work out, but that might summon the dreaded InflateError. As far as I know there's no way currently to save the "prepare for a journey" settings.
I do three wide hallways at a bare minimum. Start with two long corridors, one tile apart. With two miners, they both have a spot to dig. As soon as stone is created build a Mason's Shop. Outdoors is fine as long as your not on a Freezing map. I then queue/crank out the following:
Armor Stand (to create a barracks, so my dwarves don't decide to nap next to the river)
4 Doors
2 Tables
2 Chairs
Rock Blocks on Repeat (in anticipation of a smooth road)
The advantage of digging three wide is that the moment you get about half a screen deep, you can unselect the corridors and have your miners clean up the middle whilst furniture haulers install some doors. The doors are key to preventing the flood from creeping into your hallway and creating muddy tile woes later on.
After the doors are installed, I typically dig the corridors about seven squares at a time, building a new door at the furthest point, and demolishing the old one, until I hit the river.
Three wide is the minimum required for an indoor Trade Depot if you want to attract wagons, it's fairly simple to secure with traps as well. I widen deeper in the fortress to improve traffic flow. Five wide works until you hit a population higher than one hundred.
You can build doors to span any distance, and three wide is easy. Don't bother with the statue trick though, it's a waste of time and could get your dwarves stuck. Build a door, lock the door, then ta-dah, you can build another next to it. Just remember to unlock the door.
[ August 23, 2007: Message edited by: ktrey ]