Suo is the general term covering different types of bogs, for which there are specific names. I'm not sufficiently versed in the English terminology (I am not an expert in the Finnish terminology either if that matters) to say, what differences there are ,if any, between bog, swamp, or marsh. More likely "swamp" just has not been typed in as an alternative.
Yes! The distinctions I was hoping someone would mention! It's really quite fascinating when you get into it. I seem to recall bogs have to be slightly acidic? Need to look it all up again! As someone said, it may well not be true, but I like how "Finland" sounds like "Fen-land" because as a fen-dweller I rather like 'em.
There is still uncertainty regarding the etymology, but as far as I know, that hypothesis isn't considered particularly likely, except possibly among laypersons. I'm most inclined to believe the hypothesis that it has its root in the Proto-Balto-Slavic word źemē, which means "earth".
Both "keskellä Suomea" and "Suomen keskellä" are acceptable. The example sentence uses a very common sentence pattern in Finnish, so called existential clause (something is somewhere). On the hoof I would say, that I would use "keskellä Suomea" in the somewhere part, when the parts are in that order, but "Suomen keskellä" when the order is reversed. So
- Nuo suot ovat keskellä Suomea.
- Pihan keskellä kasvaa koivu : (literal word oder) In the centre of the yard grows a birch. (Note, a more idiomatic English way to express that would most likely be something else)
But both expressions are acceptable and widely used, so this might just be a personal preference.
I live in Keski-Suomi and I my first impression is that the bogs indeed are here. However if I talk with someone from more north, I would probably ask them to clarify if "middle Finland" means "central Finland" (=keski-suomi) or the actual middle point. I would be very surprised/confused if they mean the latter, though.
The Center of Continental Finland 89200 Puolanka https://maps.app.goo.gl/ND8VxyfE7a41hMve8