I don't have experience with the FE - didn't do it last time and not doing it this time, either - so I can't help there. As far as the reservations for the restaurants - this is completely up to you and is totally a personal preference. The only two you would need reservations for are Palo and Remy, with Remy being the more upscale (expensive) of the two. There are many who cruise without eating at either of these restaurants. There are so many other free options on board (the main dining rooms, Cabanas, room service, quick service by the pool), and some folks don't want to have to be tied into a reservation time. There are others who say that both (or either) of these restaurants are "can't miss". Palo brunch on the sea day is also an option. It's very possibly that all on-line reservations are gone by this point, but you can always try to get a reservation once on board - my understanding is that they hold some back for booking at that point.
Have you made any reservations for excursions yet? That, too, is totally optional but didn't know if it was something you had considered since you hadn't thought about the restaurant reservations?
Feel free to ask as many questions as you need to!