Generally speaking, areas on the main island are placed in three categories: Southern Part (南部 Nanbu), Middle Part (中部 Chubu), and Northern Part (北部 Hokubu). The northern part is also referred to as Yanbaru.
All Okinawans speak Japanese but many, especially older citizens, also speak Ryukyuan, a separate language, pejoratively referred to as Okinawan dialect by mainland Japanese.
Naha International Airport is the primary way to get into Okinawa Island, and is only 2 km from downtown Naha. The easiest way to Okinawa is from elsewhere in Japan: Japan Airlines and All Nippon Airways fly widebodies in every hour from Tokyo Haneda and other major domestic airports. There is only one daily flight from Narita, the main international airport in Tokyo, operated by ANA. Direct international service to Okinawa is currently limited to flights from Seoul, Taipei, Shanghai and Hong Kong.
Jetstar Asia also flies into Naha International Airport from both Osaka Kansai and Tokyo Narita.
Most travel is by car, bus or taxi, although there is a monorail in Naha that runs from the Airport to the city centre and Shuri Castle. The main road is Route 58 which runs from southern Okinawa to Nago in northern Okinawa. Route 58 is on the East China Sea side of the island. During the summer months, the volume of rental cars can make traffic very heavy on Route 58. Another good option is to rent a motorcycle. There are several companies around the island offering motorcycle rental services under the same brand 
Cycling around Okinawa island is possible but not very practical. The island is very densely populated and car traffic is heavy almost everywhere. In Japan it's customary to ride your bike on the sidewalk instead of the actual road (supposedly due to the unsafety of doing the latter), but the sidewalk has the disadvantage of having to evade other pedestrians, overgrowth, the occasional antisocially parked car, and cars pulling out of driveways. Japanese drivers are polite and not aggressive, but have a habit of often not looking where they are going when pulling out of driveways or taking corners. The terrain itself is very hilly and becomes more challenging the further you move away from the coast. If you find yourself on the east side of the island and want to go to the west side or vice versa, you will have to cross the range of steep hills that runs along the length of Okinawa. A moped or motorcycle helps to overcome this, but it's still very important to stay alert and avoid obstacles or cars.
Several buses travel routes around the island. Map
About the easiest way to get around the island though is by taking public transport. There is a large bus terminal in Naha right near Kokusai-dori which can get you to any part of the island without too much hassle. There are no signs in English however if you do your research on which busses you need to take you should be fine. Even in the busy summer months you'll usually be one of 2-3 people riding the busses.
A word of warning though, some of the farther-travelling busses tend to be fewer and further between with waits up to 2 hours for the next bus not uncommon and is particularly the case when going to the aquarium or Peace Museum. However these busses tend to be more common on the weekends (as opposed to their mainland counterparts).
Lastly, there is a monorail system within Naha starting from the airport leading all the way to Shuri Castle. Tickets are cheap and the ride is comfortable. May be crowded during rush hour though.
Being an island, there are plenty of beaches to choose from. The most highly recommended include:
With the ancient Ryukyu Kingdom which once ruled Okinawa, there were many castles located throughout the island.
Kokusaidori Street in Naha and Mihama American Village have plenty of shops. One of the popular items to buy is an Okinawan shirt, similar to Hawaiian shirts, at the Mango House, which have various locations throughout the island, but most of them in Naha.
In Okinawa, pork is very popular. A must eat is the tebichi soba, which is pig's feet with noodles. Various other Okinawan pork products are popular there.
For sushi, Yoshi's is an excellent restaurant. It is located in Chatan off Hwy 22. The Yoshi Roll is definitely worth a try! CoCo Curry House is a great cheap alternative. Try it with cheese, it's great. Although it should be noted that Yoshi's sushi is geared more to American's tastes than traditional Japanese sushi. For more traditional Okinawan sushi, Fenutin in the Mihama American Village is an excellent choice. Try the sea grapes there. They also play traditional Okinawan music there which is worth listening to, and CD's are available for purchase.
American style fast-foods and diners are popular in Okinawa. One particular chain that can be found is A&W.
For dessert, have Blue Seal ice cream. Many flavors are available, including sweet potato (beni-imo), the local flavor in Okinawa. Also, sweet potato flavored cookies are popular and can be found just about anywhere.
Orion Beer is brewed locally in Okinawa. Available in just about all stores, restaurants, bars, and many vending machines. Aside from beer, a local favorite is awamori, or aged rice wine, similar to Japanese sake. Awamori differs from sake in that the former is brewed using rice from Thailand and black yeast, while the latter typically uses locally produced rice and white yeast. Most available awamori is aged at least five years, with more expensive brews being aged fifteen. Locals consume awamori with ice and water.