Back in my day FE was so generalized it was equally frustrating for everyone as it included a little bit of everything so didn't matter what discipline you actually studied - what you studied would be a small section so most of the material was sh*t you just had to know well enough for a few multiple choice guesses. I didn't get an undergrad in engineering but did go back for a ME in Civil Eng so I took a review course at local college to prep me for the FE since I didn't rake many of the courses covered on the exam.
As for PE exam, I borrowed a copy of a study guide (very popular but can't remember the author's name now) and worked through that generally on my own.
Having said all that, you can get licensed in any discipline you want and still practice in other disciplines if you feel you have the experience and expertise to do so. although they will list which discipline you tested in, the Board does not require you to take separate tests.
Why are you looking at CE specifically? Seems like ME could be a transition option, which often doesn't require licensure for career advancement and pays better then CE.
-MarleyFeed97