Technically, the only difference between LED and LCD tv is the lighting source. Everything else is same. They market LEDs as advanced. But the truth is, its not. And electricity bills in LCD will be higher, but unnoticeable. And you will pay much higher amount if you go for a LED tv with similar configuration.
Same goes for 3d tv. Even a normal tv can work as 3d tv.
Same goes for 3d tv. Even a normal tv can work as 3d tv.