A legendary miner will be a quite fine soldier, but I suggest only using them as emergency soldiers. While they'll be extremely effective with their legendary skill and pickaxe, they have no skill at using other equipment, and it's a waste to train miners extra because mining skill doesn't train past 20. So unless you're in a pinch and/or don't normally have soldiers live to become legendary, you'll want to use regular militiadwarves. If you've got really deep soil on your map a squad of legendary miners might be a good way to tide yourself over until your real soldiers train, after which you'll still have a large amount of good miners (miners always die, so it's good to have backups) and a pile of halfway competent soldiers should you need them.
Soldiers will do combat drills in their free time, if you want them to stop those drills you have to unassign the barracks. Still, military training is really good for stress, so I don't see much need to give soldiers off time. It can be a problem with civilian militias though, since they'll often train instead of praying and socializing, which is a problem when the only training they get is relatively slow individual combat drills on off-time.
The miner-recruit has mining 19, so she's just training to get dodge, armor use, discipline, fighter, wrestling, and base stats. Then I guess she can join those "off duty" axe lords. I tried unassigning their squad from the barracks as suggested, but they're still in there doing their drills... Stress isn't a concern for them (the four axe lords are by far the happiest dwarfs in the fort, at -30k to -55k stress, happy or ecstatic), I'm just trying for a bit of natural population growth rather than raising the pop cap to get a migrant wave.
Re: flat-terrain defense discussion: I don't see how defending a flat-terrain fort is different in any way whatsoever from defending one built into a slope...
Whether the path inside starts as a ramp or a horizontal corridor, either way you'll want the same drawbridges, traps, etc. (something like Superdorf's design, for example). Could be some difference if people build above-ground structures, but people who do that will probably do so on either type of map.
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On topic: A caravan arrived! First in 18 months, thanks to that annoying zombie siege. It's only elves, but still nice to see. Saves going outside to resupply on wood. And since worn clothing is bizarrely valuable, I picked up more musical instruments on the off-chance that any dwarf will ever want to play one. Still tons more zombinite (is that the term for this particular type of "ore"?
) to sell in the fall, or summer if humans start showing up. No sign of an elven diplomat yet; probably triggered by a population threshold I haven't reached yet.
One of the zombies was a lasher, so I now have a copper whip. Are those still absurdly OP? The bug linked from the wiki says "Probable Quick Fix", was posted in 2010, last updated in 2014...
My efforts to keep weather-related bad thoughts away by burrowing the children failed. One of the kids and one adult somehow experienced rain in the past week, even though nobody has gone outside in over a year (or at least I haven't told anyone to do so, there's no reason for anyone to do so, and I haven't seen anyone do so). I've checked the entire top level of the fort tile by tile looking for any Light Above Ground indicating a hole in the ceiling, but there are none. Is this a known bug of some sort? Can rain somehow happen indoors?