I've only got one question for your plan Stagnant.
If all of your migrant waves are either smiths or soldiers...what the heck are your dwarves going to eat?
------------
I've recently started a new world and to my surprise found two goblin civilizations with a fortress each surrounded by dark pits. I stuck my fort almost right between them, the tiles nearly touching.
Anyways, I'm building a mostly above ground fort, which takes a lot of wood so the elves may be a bit upset later...but who cares, screw those guys.
Anyways, the idea is to create a large mega tower to house my dwarves in. So far we've built the base and most of the next floor, minus actual walls and a roof.
A brook runs right alongside the Tower and an underground cistern will probably be created as well as a moat. The third floor of the tower will have fortifications peeking outwards to assist in defence of the fortress as well as some ballistae.
About five floors up will be specially designed room which is essentially just a bridge and the next level stairs across it. The bridge will remain open in times of peace, however if any enemies ever break through then a lever higher up will be pulled and access to the remaining tower levels will be separated.
Just in case anyone is curious, about five of our civilizations important figures/nobles are Goblins. It's quite...odd.