Ok, some more questions kept piling up.
1. Is it just me or is the site finder really sloppy? It checks only 129 sites?
I'm often better off searching by myself. How can i stop the site finder from proposing the same locations over and over again?
It doesn't check just 129 sites; it checks 129 world tiles, each of which is made up of 256 region tiles (in 16x16 blocks). Your map's dimensions are in region tiles, so the finder checks every possible location for the map you've told it to.
That isn't to say it's not sloppy, however; it checks every region for a match, then just spits out the first match it finds. This is also the reason for the last problem, in that it just keeps spitting out the first match even though it searched through all of the maps. The way to stop it from giving the same match repeatedly is to change your search parameters. Start with the parameters you really want (say, underground water and a magma pipe), then if you don't like the map it spits out, check the biomes and features of that map and exclude them (for instance, if you find yourself on a biome with no trees, set yourself to high or medium rainfall). With the former match no longer valid, it won't get chosen again unless there's no new valid matches, in which case it might.
2. Next fortress is going to be an upstairs fortress. Means the fortress is made up out of construction and the ground level contains only a receptionist and defense. The real fortress starts on floor one. The whole thing is built on top of a brook.
Here are my pitfalls so far:
No engraving or smoothing available. Room value drops significantly.
There's a couple of options. First, use higher-value materials for walls and floors where value is needed. Second, use bigger rooms. Third, use statues or windows for your "walls" except for where you need doorframes; these things have quality modifiers and actually have a higher item value multiplier than engravings, but can get knocked down by buildingdestroyers or tantruming/berserk dwarves. The buildingdestroyer point can be very important, because buildingdestroyers apparently constantly path to every building they can destroy that they can reach, so their presence can ruin your FPS if you have many, many statues (I had a fort where I used statues for all walls. Giants (from the Relentless Assault mod) showed up. My FPS went from 200 to 1. Bad Times.).
Every usable tile has to be constructed. 7 Masons are mandatory ofc.
No underground crops.
Big material consumption.
Any aditional input on this idea?
Building aboveground is much, much slower than excavating underground forts. Fulfill your needs for survival, then have everybody else either produce building materials or build. It's the only way to get an even reasonable speed out of this thing.
Aboveground crops are actually somewhat more efficient and effective than UG crops for the most part, as all of them can grow during any season if you put a roof over them. Do note, however, that biomes that have no natural plants (mountains are the most commonly problematic) will not grow AG plants at all, even in a muddied greenhouse.
3. I already tested the idea of making floor tiles muddy using screw pumps and it worked out ok. But:
Can i do this easier with the pond zone water dumping?
Easier? No, not really. It takes less setup to start, but much more micromanagement, and is much less water-efficient unless you do even more micromanagement, takes longer overall, and once you're done the whole setup is totally useless. At least pump irrigation systems can be repurposed for other waterworks.