Not to derail the thread, but you can build a very efficient fortress in about 4 levels, so there is no reason to breach the caverns... ever if you don't feel like it. The only time I've accidentally breached the caverns is when I had a really deep aquifer and the last layer was the first layer of the caverns. I guess the main reason to dig down is magma, but if you're doing that, then it's really a choice. The timing of when you are going to do that is up to you.
Having said that, assuming you want to play aggressively, does it make sense to have a few highly trained, full time warriors, or a whole group of reasonably trained warriors? In adventure mode, my impression is that the most important skill is actually fighter. But my recent testing with dual wielding leads me to believe that observation is quite important for getting good opportunities. Also, given that you are unlikely to be able to afford metal armour at the beginning of the game, it seems like a combination of fighter, observation and dodging might be enough. Novice shield level (which you can train up pretty quickly) seems to be adequate for the vast majority of what you are going to run into early-game). You could give that to your starting seven and still have a fair amount of points left.
Lately I have been starting out with all peasants because there are virtually no skills that are worth getting on embark, apart from situational ones -- for example mining if you need to dig a safety hole quickly. I can't remember if masonry/mechanic affects the speed of building, but if it does it might be valuable for getting a bridge up quickly -- still in those situations it's probably better just to embark with blocks and to wall yourself in immediately.