Give the contents of wikipedia to our own civilization a century ago and watch the outstanding progress. A lot of theories wouldn't need to be tested, once the accuracy of wikipedia was determined. Things like penicilin wouldn't have to be discovered by accident. Several chemical reactions, which are named after their inventors, wouldn't need discovering.
Several open questions would be answered in an instant. Heck, give wikipedia to us a decade ago, we hadn't even discovered exoplanets. That would tell us that they are out there, and the outlines of basic techniques to find them.
Even things like the best reentry shape for a spaceship. Or chemical elements previously undiscovered.
WRT that particular entry, it is in fact, very abstract. But give it to a university, no matter the tech level, they will figure it out, given time. There's a lot of missing information indeed, but people are very good at filling in the blanks.
I'll give you another example: http://en.wikipedia.org/wiki/Laser . It is cryptic too, but remember that the laser, once conceived theoretically, didn't have a practical use. Now, we can't live without them. That entry lists the practical uses right there.
There are many, many more examples. My argument is that, while you cannot give wikipedia to someone and expect that a civilization will come out on the other end, the knowledge that is there is priceless. That would require work, but I bet any reasonable government would provide the necessary financing.
Oh, almost forgot, weaponry. It has several outlines for weapons. Heck, even the type of antenna best used for radar would be enough information to completely change the events of the World Wars.
Another thing I just remembered: http://en.wikipedia.org/wiki/Helicopter . Helicopters were attempted for decades with no success, it says right there in the history section. But someone came up with the idea of flexible rotors. There, my last phrase is enough to point a team to the solution, even if the details about materials, manufacturing methods and the calculations are missing. But I bet people can figure it out.
It sounds like you are saying Science would have put faith into the accuracy of a single book. The methods of discovery are as important as the discovery itself.
Remember that a large part of the reverence that we have for "the ancients" is because there was a long stretch of time during the middle ages in which old knowledge that had disappeared was rediscovered. The scholastics/etc. were all about finding old books from Greek/Roman times and learning from them, much more than creating new discoveries.
And this made sense at the time, as it would if all of our technology and knowledge were gone.
Have you heard of Simple English Wikipedia? It does describe (e.g.) electricity in a useful way.
I've tried learning both math and physics from the Wikipedia and most of the time I've enjoyed it. If I'm feeling frustrated on an article(I know the feeling you have described) it usually means I should read about more basic stuff first (the stuff which is conveniently linked in the article for me).
What do you think useful information about electricity should look like?
Imagine for instance that you don't know what electricity is. Now read https://en.wikipedia.org/wiki/Electricity. There is no useful information there. Looking around now, I can't figure out any way I could come to any sort of reasonable understanding. This is a familiar feeling for me - it's the same feeling I get whenever I look up some new (to me) mathematical concept on wikipedia.
Wikipedia is not meant for teaching. Now, a wikipedia of textbooks (wikiversity?) would be extraordinarily helpful in an apocalypse, as well as every-day life.