So, an initial forum search in the DF mode discussion section didn't of course really turn up anything, searches in this forum turned up a bunch of more specific info, thanks to which I could make some guesses about this stuff, but I thought I'd make a new thread anyway and consolidate some of the info in one place. Oh, and the wiki either doesn't even mention or isn't very exact/unambiguous about this stuff, mostly. So yea, I'm looking for clarifications/info on a bunch of stuff regarding the things in the thread title.
Background: my most recent fort has a volcano, sand and clay (and regular soil), is mostly wilderness but with some flat, only-soil&no metals haunted mountains to the NW (no idea what they'll do, I've only embarked&saved). The other 2 biomes have some wood, flux stone but only deep metals, so I foresee obsidian, earthenware and green glass aplenty, since I don't like to dig very deep right away. Brought a lot of bronze ores, so that should help with the metal.
Some of the questions are about dumping into magma, some arise from my plans to cast a cube of magma that I'll carve my aboveground fortress out of, maybe later doing something similar for at least a section of the underground fortress too. And the slightly-less-related-to-the-other-topics-but-relevant-in-my-embark section is about evil biomes and their effects.
So, onto the questions (might not remember everything at once of course):
Regarding magma and item destruction...
1. Do all volcanoes/magma pipes/pools have semi-molten rock at the bottom, for every tile of the cross-section of the magma pipe? (as I understand it, SMR destroys anything that lands on it, completely)?
2. Partially/Maybe the same as above: What gets destroyed upon dumping into magma, when the magma is natural, ie. magma sea/volcano/magma pipe?
3. What gets destroyed when dumped into magma that's been moved into artificial reservoirs/channels?
Regarding obsidian casting...
4. Does it matter if you dump water onto magma or magma onto water?
5. If I pour some water into a deep artificial reservoir of magma (or vice versa, see previous question), does the obsidian form at the bottom, or at the top? Does it matter if the obsidian-to-be would be supported, ie. does it form at the top at the edges, but the bottom otherwise? If it is/can be cast at the edges at the top, can this be used to block up the volcano's top z-level?
6. Is steam still harmless?
7. The wiki mentions the consequences for items in a square that gets obsidian cast in it ("most non-magma safe items are destroyed"), but what about channeled/dug ramps, constructions, and other stuff (buildings?)? If/When I dig out the obsidian, will the constructions become visible again? Will their materials keep haunting my stocks screen, or will they get destroyed completely?
8. I was planning to carve my aboveground fortress out of cast obsidian for smoothing&engraving. Will rooms dug out in the towers/buildings in the aboveground fort count as dark subterranean, or inside light aboveground, or what? A possible but not certain-to-be-implemented idea was to have the entire aboveground fort be a roofed-in (well, the roof is cast, but anyway) bunker, but this would suck if it would basically cause just about everyone to be cave-adapted (my training barracks usually end up in aboveground sections of the fort to avoid this).
9. Should I/How soon should I take precautions against critters coming up the volcano and attacking my fort?
Regarding the haunted mountains, and the FUN I'll have with that (it's my first embark to include an evil biome...)
10. I've read of fog that turns creatures into husks, (harmless?) rains of blood, and at least nauseating weather, and evil regions that renanimates any corpses in them to zombies. What other effects are possible from the weather (syndromes? contaminants that can spread the effects outside the area?)?
11. I understand that the reanimation only occurs within the biome itself, although zombies (and creatures spawned in the haunted area) can wander outside. Can the weather wander outside the biome? Into my fort? Through doors/raised bridges? Does evil weather also spawn in the underground parts of that biome (in the caverns, maybe?)?
12. Are evil biome effects limited on severity depending on if the biome is sinister/haunted/terrifying? Is there always only one effect/how many/is there a limit to how many of the aforementioned (or not mentioned) can happen in one biome in an embark?
13. Regarding #10, I understand skeletal (giant) eagles are fun, hence the bunker idea in #8
Which brings me to this question: can spawned wildlife turn into husks/zombies, for a larger variety of flying undead creatures?
14. So we don't end on 13 (I'm not usually superstitious, but this is DF, and it's best to cover all my bases), I guess magma doesn't really do anything to any undead, other than set them on fire? What about goblins/other invaders - I guess it kills them and destroys their corpses and non-magma-safe equipment?
Others can of course feel free to add more questions. I'll try to keep this first post updated with answers and additional questions (please number them) for ease of looking up, and I guess as a price for making a new thread about this, I might add the best clarifications and new info to the wiki, too.