Say I wanted to reference a passed WA resolution in my nation's history (in this particular case, I wish to reference The Landmine Convention and its affect on the manufacturing and deployment of Novraslav landmines), may I ask how I would go about in dating such a topic in an in-character perspective? Since the resolution was implemented on 19 March 2009, could I safely assume that in the "in-character world" it was implemented on 19 March 2009 and continue my article accordingly? Or is there no rule, official or unofficial, concerning such matters?
There is no official rule. If your country follows the In Character timeline (i.e. it is 2012 now) that makes most sense for your country. If you are a future tech nation or simply a nation on a different calendar you might want to make a conversion. It makes little sense to pretend the thing we voted on just last week has been enforced for centuries.
Ideological Bulwark #7 - RPed population preserves relative population sizes. Webgame population / 100 is used by default. If this doesn't work for you and it is relevant to our RP, please TG.