Uh, that's a big project indeed, but I dont think it's "crazy" - I plan to build this model myself (beginning next year). Yup, I'll be wathing your progress very carefully..
Anyway, expression "gun boat" is not proper in this context, I believe it should be for example "24 lb. cannon" For proper naming/translating (you will have to name probably K+ parts) is good to use "Dictionnaire GRUSS de Marine" - book is rare and hard to buy, but very useful for people that have anything to do with the ships.
"AFAIK the source of all sources" of data about this ship is Maritime Museum in Paris, @Trocadero. They have a big model there (is this model on your photos 2 & 3 ?), which is a base for all other models/kits available. That's true also for my own reference: 1/100 Heller/Humbrol plastic kit. But real life models aren't best source for the reference data about materials... I believe the barrel should be darker, almost black, with yellow highlight.
I hope my remarks are more helpful than annoying
