So I found out the hard way that Elves don't like when you offer wooden art for trade
Not only that, but they'll reject anything that was produced using wood too. So don't try to offer them charcoal, lye, ash, potash, pearlash or anything made from those things, like soap (uses lye), clear glass or crystal glass (uses potash).
Also things that are decorated with wood. : D
Things that you made suing charcoal as a fuel are fine though, since they won't know whether you used charcoal or normal coal for it.
that channeling swampy water holes doesn't really increase the amount of available freshwater but dries them out rather
This is why rivers and aquifers are useful. Although even murky pools will eventually replenish due to rainwater :3
and that terrifying Werelizards are actually just human adventurers who try to scare Dwarves to steal their treasures
Werecreatures are a bit odd in Fortress mode, due to the fact that they'll be in their normal harmless form unless there's a full moon, and time passes so quickly that this will only be the case for a few minutes at most. It also means that most of the time when a werebeast attacks you, it'll be in its normal form.
They're a lot more problematic when one of your inhabitants is the werebeast in question. If that happens you'll occasionally find mysteriously murdered dwarves lying around. c:
I know that stockpiles are actually cluttering the stocks even more than leaving stuff where it is but I tend to use them to provide easy access to resources for workshops and as a visible indicator of available resource amounts
That's their main purpose. You can also reduce the amount of space that is necessary by making bins. Dwarves will place small items inside the bin. That way your metal bars and dolomite toy boats will only take up one tile every dozen or so, rather than one tile each. The same is true for food which can be stored in barrels or pots and seeds which can be stored in bags. And I think multiple seed bags can be stored in barrels too...
I had my first famine last winter and the children were the ones to keep the nation alive by hunting vermin for food
The "hunting vermin for food" message refers to individual dwarves getting so desperate that they start eating rats or worms or other small critters from the floor. They won't actually be able to sustain anybody other than themselves that way. If even.
I'm still not sure whether my butcher actually slaughters the pastured animals or only those I set up as ready to be slaughtered because he keeps telling me he can't find enough butcherable animals nearby
If your butcher can't find any animals to slaughter, then there aren't any animals that have been designated for slaughter. They'll only ever slaughter those that you specifically tell them to. So there's also no risk of someone's pet accidentally getting butchered (it's not possible to set a pet slaughterable). You don't even have to specifically give the order to "butcher animal" just mark the cattle you want to have slaughtered, and your butcher will do the rest. It's helpful to build a tannery next to the butchery and enable tanning on your butcher as well. That way he'll immediately and automatically proceed to tan the resulting hide, and you don't have to worry about the hide rotting and filling up your slaughterhouse with miasma.
Also I can't seem to get enough useable seeds for my farms, nor do I have a clue about the right size of farming spots.
The size of farms doesn't terribly matter. I usually go with something like 3*5 and have a couple of those, where I plant different things.
Take note what kind of seeds you have available. Different crops need different conditions. There a subterranean crops which can only be grown underground, and above-ground crops which have to be grown... above ground. Most crops can also only be grown during certain seasons. Except plump helmets, which can basically be grown all year round. But only below the surface.
To keep track of the actual stocks I found the hardest thing to do, because the list is so endless that you miss the important items easily
If you press t, you get a building stock menu, which displays every item present in the workshop you hover over (including the materials that have been used to construct the building). This is often an easier way to take stock than looking over the Fortress wide items list (Which lists literally EVERYTHING present on the map, even if it doesn't belong to you). If you press k, you can also have a look at what's lying around on the tile you hover over. That way you can have a look around your stockpile.