A little tidbit towards King of Weasels: While I'm not that great at figuring out maths on CG's level, I do know my chemistry and can tell you that medieval gunpowder could not be used to make TNT or any high explosive for that matter.
What you can do is to refine it: make into granulate, try grinding it up into fine powder, all manner of adjustments to the components and the actual way of burning it and storing it.
Mind you, these things took a lot of time to figure out and despite their triviality, they actually do matter and improve the powder. for example, granulate is used in handguns because of the ease of storage ansd measuring, while fine powder is used in cannons and has better characteristics because of greater surface area of the material. also, the actual chemical composition also matters and some powders may have less or more sulphur or charcoal, depending on the actual use.
I don't want to discourage you though, I just want the game to progress evenly. We can't go from firecrakers to plastic explosive in span of couple of years.
Ok, now that my tirade is over, I think most of the things are sorted, although most of us are probably busy with work/education. Not to worry though, trade discussion is over for now (hopefully) so things will pick up again and I will do some actions as well. They will be most likely tade so CG, you might have something to do. I'm just waiting till summer though, for better wool prices in the capital.