Thanks for all your help. Slight update:
A few more caravans have come by, which means a few more ambushes and an invasion have happened. My fortifications and moat is complete, which means my dwarves are safe to wander around outside even when an invasion is out there.
Notes: A dwarf is caught in the open by goblin bowmen and killed. My crossbowmen (who are standing near my entrance waiting for all the slower dwarves to get inside my defenses), decide that this is a good time to go pick up the dead dwarf's equipment one at a time. It took the life of one dwarf for me to figure out how to make them realize that this is not a good idea. Their job becomes "Pick up Equipment", so I can't stop it. I order them to station or move, but they decide they want to pick up the equipment which is behind 2 squads of goblins before they station. So, I finally get the idea to create an alert that forces them into a burrow inside the walls, which means they insta-change clothes, but finally it brought everybody back inside the walls. I think these dwarves need a little more common sense. If you see something you want out behind enemy lines, it might not be the best idea to charge out their alone to attempt to collect it, going past the squads of goblin bowmen. Luckily, only one died before two more (well-trained because they were hunters previously) were out there and actually managed to stun and severely injure most of the squad, and the rest retreated (I gave them copper and steel bolts by this time). So I charged down really quick with my 2 melee squads, finished them off, and ran back into the walls and raised the bridges before the other gobs could get there.
Which leads me to a question. I then order my crossbowmen to patrol the southwest wall, which another goblin squad happens to be near. They oblige, but only one of them actually brings bolts with him.... What? Aren't the crossbowmen supposed to resupply if they have no other standing orders? Mine certainly didn't, I checked. Three of them stood on that wall staring at the goblins less than 5 tiles from them until they got thirsty and went to get a drink... Now, I wasn't in a big hurry because my civilians were still wandering freely in my compound gathering crops, cutting trees and whatnot since they were perfectly safe in the walls, but I found it annoying that I had to stare at goblins for several minutes.
Finally, the one dwarf with bolts gets up there, breaks the legs of one, kills another, and they run screaming. By that time, the one other goblin squad of spearmen decide they've seen enough and make a break for it too. So I killed 4 reachable goblins and lost a total of 3 dwarves, a crossbowmen and two civs. Let me explain that previous statement. 8 goblins, yes 8, drowned in the moat when it thawed for spring. They were standing on the frozen moat trying to find a way past my walls. While hilarious, it robbed me of the chance to loot them because my moat is fed directly from the creek with nothing inbetween.
In short, the things I draw from this experience.
1) I have several very experienced crossbowdwarves now, and they rock pretty hard with metal bolts. So thanks for that. That the two experienced ones were actually able to only be injured in the fight with the goblin bow squad was a welcome sight to see.
2) Why don't they actually carry the bolts I've assigned to them for combat use in the military->ammunition menu? I have wooden bolts for training, and metal bolts for combat. The numbers shouldn't be a problem, I have over 500 metal bolts assigned to the squad. And there are many checkmarks next to various stacks of bolts, so I know they're assigned. Once they run out, it takes them forever to pick up new ones. Sometimes they're not even doing anything in the meantime.