True-all the above.
Best book I've seen in Boarding Time--by Morrison. Your own program should also have several resources. Best way to prepare yourself from what I understand is to simply just practice practice practice.
My own program director went to a convention in New Orleans a few weeks ago where they mentioned this very issue and yes its only the current PGY Is that don't have to take the oral boards.
If you are above a PGY-I, it will be possible to avoid the official oral boards if you are willing to wait it out, because at some point in the future, the oral boards will be phased out for everybody. I don't know how long that will be, and I believe you would still have to get a residency program to offer you an equivalent board exam that you have to pass. This is appealing to some because its more comfortable to have an old attending give this instead of a stranger. Add to that there's a lot of horror stories with the oral boards. I don't know how much merit there are to these horror stories.
If you want to wait it out, I don't know how long it'll be, and that could mean less pay as a non-board certified doctor. In the NJ state sytem, (and I don't have the exact numbers, these are approximations), I believe the pay difference between a certified & non-certified doctor is about $30,000/year.
I'm not looking forward to the oral boards. Mostly because my own experience with oral exams makes me dislike the subjective nature of them. I remember in medschool, a doctor during Clinical Skills would mention how to do a specific physical exam, and I got it down the exact way that doctor told me how to do it. Then during the oral exam, I did it the same exact way, and the examiner mentioned to me that I had it all wrong, and this doctor showed me the "right" way to do it. Then I do it that way, and got another doctor & he tells me I'm wrong, and shows me his "right" way to do it.
My own program had a bunch of doctors pulling a similar thing, so we made it a policy that only doctors that are national board examiners conduct mock boards.