Is it ready to use out of the box?

Yes. The surface is seasoned at the foundry, so you can cook in it right away. Wash it, dry it fully and rub in a little oil before the first use.

How does it differ from a standard skillet?

It has two short handles instead of one long handle and a helper handle. That makes it easier to lift with both hands, but you lose the long handle for tossing and one-handed work.

Can it go in the oven and on a grill?

Yes. Cast iron is oven-safe and works on grills and over a campfire. Use mitts, since the handles get hot.

How do I clean and care for it?

Hand wash with hot water and a stiff brush, dry it fully on the stove, then rub in a thin layer of oil. Avoid soaking it or putting it in the dishwasher.

Will it work on a glass-top stove?

It can, but the flat base and weight need care so the surface is not scratched. Heat it gradually, since cast iron can heat unevenly on electric and glass tops.