Depends on where you are in the game. The further you get the more goods you should try to have, as the needs for resources increase with each new age.
After reading the linked page, I think it might be a good idea to try and switch. Seems like all wikis will be switched eventaully, so the sooner we check and make sure there will be no issues with our wiki - the better.
The total cost of each province building is listed on the Guild Battlegrounds page, in a table. As explained in the section about province buildings the exact costs are random and vary based on the ages of all guild members, so it's impossible to list anything more than total cost.
I'm having trouble remembering the exact time I got this quest. I remember I got Version I, but... well, at first I was only negotiating, until I got the side quest "An Offer You Can't Refuse III" and completed it. Still, based on the next quests, I believe Version I is the peaceful version and Version II is if you used force previously - because the quest "Declaration of War" seems less demanding than the quest "All-Out War".