Tokyo Disneyland is a full-scale Disney theme park sitting just outside Tokyo in Urayasu City, Chiba — Asia's most visited theme park. But its sister park, Tokyo DisneySea, does what Disneyland can't.
Tokyo Disneyland is the world's most popular Disney park by attendance — and it shows. Right next to it, Tokyo DisneySea is an only-in-Japan theme park with unique rides and theming you cannot find anywhere else on earth. That split is the real decision: one park is globally familiar, the other is a reason to fly here.
Only if you're travelling with young children who specifically want classic Disney — otherwise, Tokyo DisneySea is the same trip distance but offers an experience you can't replicate at any other Disney park in the world.
No — both parks are ticketed and represent a significant day spend; prices move, so check the official Tokyo Disney Resort site for current admission.
We'd redirect the question: book DisneySea instead, go on a weekday, and stay in central Tokyo rather than a 'Tokyo Bay' hotel — the transit is manageable and you'll keep your base useful for the rest of your trip.