Is a Gibson worth the price? I was hoping someone who's played both could tell me if there's a difference between the two besides name and price. And does anyone know how a Casino is for lead or rhythm?
... The Gibson is much much much better quality. The only Epiphone Id suggest would be the Sheraton. Its just my taste but the ES335 is beutiful.
There is no such thing as a lead or rhythm guitar. It's what you play on it.

And honestly, it depends on whether YOU are willing to spend that much. You could get an Elitist for half the price and pretty much the same quality. Same goes for Edwards and other copies. BUT a Gibson retains value a helluva lot better.

Go out. Play them. Decide.
Well, the Sheraton is actually an original by Epiphone and not a "cheap Gibson copy." The Elitist Sheratons come with mini-humbuckers I believe, a bit punchier than normal ones, which is John Lee Hooker's signature sound. I believe I he used both the original Sheraton's and the II's. And the inlays are pretty damn fine as well.
how is the weight of a hollow body compared to a Les Paul, is there a difference in weight (I'm guessing since it's hollow it is but I might be wrong)
It's lighter. It's only a bit heavier than an acoustic. The difference in weight between a semi-hollow and a full hollow isn't that large either.