In my opinion, Focused and Fearless
is probably the one you should get first. Shaila does a good job of describing and guiding you through the aspects of jhana in general, where Brahm's book is pretty focused on his particular perspective. Perhaps take a look at this thread? viewtopic.php?f=17&t=400
As for trying not to interpret things incorrectly, you've got to remedy that possibility by gathering as much information as you can on the subject and supplementing it with plenty of personal meditative experience. Meditation and the jhanas are something of a subjective thing, so you need to learn what phenomena accompany the deepening of concentration for you personally. I think there's more than enough good information out there that when mixed with a diligent practice, can give results.