There are lots of RV publications - for example: RV'ing for Dummies. I've got a few in my camper at present - RV Vacations, and a few others. All seem to have basic background information for the various types of RV, then info. on planning your trips, where to stay, etc.
RV-101 has a lot of good info. I downloaded the 'book' for Popup Trailers, although most of the information was the same as my owners manual.
As to RV web-sites and/or camping web-sites, I visit RV.net daily as well as this site, a woman's RV forum, Family Camping Chat (I'm a moderator), and several others (Pop-Up Portal, PUX, Arvee.com).
As to Magazines/other publications, as a member of Good Sam Club, I receive Highways Magazine and do actually read the articles. As a Thousand Trails/Outdoor World Member, I enjoy reading TrailBlazer.
I have purchased the Good Sam Club's - TrailerLife Directory, and it has been extremely valuable with all kinds of RV information, as well as information of campgrounds (very few missing). If not using my membership campgrounds, I will refer to the TL Directory, then, after selecting a campground, will go to the web-site: RVParkreviews.com to get a real picture of the campground from folks who've actually camped there. (TL Directory and Woodalls have a rating system, but it really doesn't do justice). I do not plan to purchase another directory (member price $12.50, non-member $25.00)) as in my opinion little changes in a year or two that I couldn't find online for free.