Seems to me that there's a different definition of 'dry' firewood here than in the States. I wouldn't even consider burning any wood, except for maybe dead standing in some cases, that hasn't been in proper storage (with lots of wind exposure and preferrably a good cover) for at least two years.
Also, I don't really get how wood can be better (like in 'seasoned') than dry. To me, dry means dry enough to burn properly, and it usually doesn't get better than that unless you use a kiln.
On topic: I usually mix in spruce and fir with better quality firewood, and make sure the fire roars. I also think creosote is a result of a 'suffocated' fire and the moisture content, rather than of the type of firewood. Not giving the fire enougn oxygen also results in elevated levels of carbon monoxide, dust particles, etc etc. Whether that's a big problem or not depends on the amount of people living close to you, I guess, and the quality of your chimney setup, as CO can also be 'pushed back' into your living room.
The water vapour of too moist wood will condense in your chimney, especially when you start the fire, and dust and other particles will stick to that.
I almost never have to clean my stove glass, and it's definitely never black. I sweep once a year (insulated 'double-walled' stajnless steel chimney) and almost nothing comes out.