I know a little about the design. Some of the electronics had to move to mitigate gunfire loads, some of the sub-contractors took a lot of time to accept the "economy of scale" mandates, etc... so flushing out weight is just now being worked.
Typically, Designers concentrate first on getting systems to work. Bench-testing (for lack of a better term) eventually proves a design and the weight is attacked later.
I agree "later" has come; I disagree there is no margin. While there are critical areas fat, there are other areas still to trim. I don't expect weight issues to be resolved anytime in the next 12-18months.
The Navy didn't want on board from the start, right? ...as I understood it. But they continue to be present, talking the details at every review.
I'm not privy to the fuel situation; is this a product of being overweight or poor engine performance?
The engine is a monster. Very powerful and efficient. Take a look at the airframe; notice that there is almost no room for gas. That big engine, while efficient as it gets, still sucks gas like all big turbofans, which is considerable.
What you have here is the Harrier fiasco all over again. Some jokers in the Pentagon fall in love with STOL, regardless of the fact that there is no tactical advantage to be gained. It just has a "cool factor", which does not hold up under combat conditions. The survivability rate for the Harrier (and I believe is also true of the JSF) is terrible, to the point where one could argue that you could bring down a Harrier with a well placed rock.
JSF is a nice air-show airplane. When you hang heavy ordinance on it and fill a couple of wing tanks, it becomes a single-engine slug, looking for a mission.