The countries currently subject to a US travel ban are Iran, North Korea, Syria, Libya, Yemen, Somalia, and Venezuela. This list is subject to change so it's always best to check with official sources for the most up-to-date information.
cuba
No, the US has no jurisdiction on what other countries do.
http://travel.state.gov/travel/cis_pa_tw/tw/tw_1764.html go to that site. it has it all
No, it is not possible for US citizens to travel to North Korea as the US government has issued a travel ban to the country due to safety concerns.
Yes, US citizens can travel to certain countries without a visa.
All countries in Europe
With a US visa, you can travel to the United States, but the specific countries you can visit will depend on the type of visa you have.
You can travel to as many countries as you like. All you need is a passport, and enough money and free time. Some countries ban there citizens from travelling to some other countries, for example citizens of Arab countries are banned from going to Israel, US citizens are banned from going to Cuba.
The right to travel with a US passport is one benefit of being a citizen of the US. US citizens need a passport to travel to other countries.
Some countries or US states have totally banned the use of flash drives (and other removable media) by governmental organizations.
With a US visa, you can travel to various countries around the world, but the specific countries you can visit will depend on the type of visa you have. It is important to check the visa requirements of the country you plan to visit before traveling.
No. The US did not, and never planned, to ban GTA V.