I'm fairly old to be starting a PhD program, but I live simply and I'm easy to satisfy. I took a huge pay cut and a gave up a steady research job to pursue experimental psych but I'm perfectly happy with that (for now). In this case, job security and income aren't all that important to me - YMMV (will vary!!!).
Just make sure you are as honest with yourself as possible about what the likely outcomes of your switch will be and try to estimate if you will be satisfied with those outcomes!
I think approaching it from the angle of "I probably already know more than them" isn't really going to be productive in a science which is highly collaborative... Same problem with those who don't feel the need to discuss science with those who are slightly out of one's research bubble.
Being amicable is part of the job, or at least for those who are successful at it.
Another vote for the Andy Field book (Discovering Statistics Using SPSS) - this book is mostly an intro text but it really digs deep to explain what you are in fact looking at when using inferential statistics and how to ensure that you aren't going to report artifacts instead of meaningful differences!
Added: I think it is also critical to have at least one text that will help you with your analysis program of choice (SPSS, SAS, Stata, R, etc.) - perfect practice makes perfect