Is the Grumpy watch worth $642.04?

Only if you want the Disney Parks exclusivity. The J810 Eco-Drive movement and mineral crystal are ordinary at that price; comparable non-character Citizen Eco-Drive watches sell for far less. Buy it as a collectible, not as value for the movement.

Does it need a battery?

No. Eco-Drive runs on a rechargeable cell charged by light, so it keeps time as long as it sees regular light. Leaving it in a drawer for weeks can drain it; set it near a window to recharge.

Yes. It is rated to 100m, which covers swimming and showering. The leather strap is the weak point in water, so rinse and dry it after pool or salt water.

How does the 43mm case fit?

43mm is a mid-size case that suits most men's wrists and larger women's wrists. The overall length is about 255–260mm, so check your wrist size if you are near the end of the strap holes.

Is this the same as a standard Citizen Eco-Drive?

The movement is the same J810 base used in regular Citizen three-hand day/date models. The difference is the Disney Parks dial art, caseback logos and the limited retail channel.

With only 2 stores listing it new, discounts are unlikely. Watch for resale listings from park visitors, and compare against the other store's price before buying at $642.04.