Actually, It depends on the country in which the Copyright is held… In the US and Also In some European Countries, If I provide something for Free… It will lose copyright protection. The same goes for Trade Secrets, (I was recently on a Jury in a court case involving copyrights, trademarks and Trade Secrets, and over 200 Million USD was at stake in the trial. So believe me when I say that I do know a little of what Im talking about here… As It was explained to us VERY clearly) Basically, By releasing the data or image for free they lose their protections and exclusive entitlements to it. Because by providing it for free they are saying that the product has no monetary value. That Said. Other countries are totally different as well as international Copyright laws. They state that you actually can NEVER lose a copyright unless you purposly release the right to your entitlements in written form. GW tends to default to International Copyright Laws.
When it comes to art… Usually GW doesn’t actually own rights to it. but rather leases it from the original artist. They are usually protecting the artists rights to the art as well as their being as they commissioned the art.
That said there are ways around much of copyright.
As far as rules and such in accords to warhammer… So long as the information given by a person is not to such specifics for a third party to NOT require a purchase of the original publication. All is fine… so for example: Saying that Ratmen Slaves can take x, y, z, and r upgrades. would be perfectly acceptable… and even the points… but if you put the entry, stat line, points, options, special rules, etc… you are in violation of a owners entitlement to I.P.
As far as art/concepts… its a very slippery slope. There are a few things you can do to basically use what ever art/concept you wish.
The main ones are, Uses to display the original for educational or historical purposes & use as humour (Spoofing, etc)
Usually you have to meet one or more of many minor requirements… the main one is reproduced original is not in a size or quality sufficient for printing…
What It all comes down to in the end… is sure there are alot of Laws involving the legal usage of IP… and for all purposes a site could be respecting every one of them… but if the owner of the IP comes a knocking and asks you to take it down and try to assure it doesnt happen again, normally you take the request and do it. Out of respect. If you dont… you risk your chances going to court and relying on a Judge to interpert the laws the same way you do.
As far as the point of saying the Administration / Owners are not responsible for content… your greatly incorrect… A Disclaimer is simply that… A small amount of information stating things that are not claimed but owners or Administration. They are not considered legal documents or contracts. No one has to agree to your disclaimer. Now… if you make a EULA saying you are not responsible they you are correct… as these are deemed by most countries to be considered legal contracts. But those are very clear and you MUST accept to them before continuing to a point where you could post said information…