A-Z. This is quite routine. Taxi's can be expensive. The starting rate is 660 yen and this will take you 2 km. The meter then quickly mounts up. At night time be prepared for steeper charges.
Most stations have a taxi rank or a taxi can be hailed from the roadside.
A red light means vacant, a yellow light means not available. The green light means the night time surcharge is in operation. With heavy traffic, expensive toll roads and a terrible parking problem, driving through Tokyo is not a good idea. From discount stores you can buy a bicycle for as little as ten thousand yen. If you plan to stay in Tokyo for a while, both in terms of convenience and exploring your local area, it's well worth the investment.