In general, I like your idea. How much interest there will be in the wider RPG community? I'm clueless on that.
I'm guessing that you've already done your research on this, so I may be preaching to the choir in what follows.
If you want it to fit into the general Middle Ages / Rennaisance ambience of most D&D adventures, instead of the multi-page publication you have proposed, you might want to consider the single-page broadsheets that were the forerunners of the newspapers we know today.
Since you mentioned advertisements, I'm guessing you will be concentrating on local issues and businesses along the line of "Hooligans From the Market Square Fracas Last Week are Sentenced to 3 Days in the Stocks. Per the Magistrate's ruling, where he admonished the louts, "As ye sow, so shall ye reap", ruined produce from their scurrilous rampage is available for a small fee, if you feel so inclined as to want to pelt the miscreants with it. All Proceeds are to go to Recompense the Wronged Merchants by Order of the Court." and "Worter's Cooperage - Best Made Kegs Anywhere - You'll Get Your Silver's Worth at Worter's on Tonkin Lane".
There was at least as much disagreement about politics, religion, etc., in the past as we have today, so by producing shorter pieces, you can provide opposing viewpoints put forward by different factions. Neutrality in print may have existed at times, but then as now, it's the need to have one's perspective heard and acknowledged that drives anyone to (When I hear people complaining about the mud-slinging in politics these days, I wonder what planet they're from; there has never been a shortage of it.)
So the small business advertisements and local news stories can be made generic more easily than the impassioned viewpoints stuff. In either case, maybe using a fill-in-the-blank option in the articles, ads, and editorials for names of locations, factions, principle NPCs, and the like, would be the way to go.
Mind you, the earliest publication considered to be a newspaper was, according to The Timeline of the Newspaper Industry (
http://inventors.about.com/od/pstartinventions/a/printing_4.htm), the Acta Diurna, first published in Rome in 59 BCE. A monthly newspaper (Notizie Scritte) began publication in Venice in 1556, and the first printed weekly newspaper (Relation) started up in Antwerp in 1606.
A couple of the other sources I looked at after reading the OP are:
https://en.wikipedia.org/wiki/History_of_newspapers_and_magazines
and
http://www.bing.com/images/search?q...history+of+newspaper+advertisements&FORM=IGRE