More info
For types of visas, check out
http://travel.state.gov/visa/temp/types/types_1286.htmlYou will see that for Tourism, you will need a B-2 Visa which is issued at the border. I cannot find anywhere that states the time you are allowed to stay, but I believe it is ~180 days right now with a proposed extension of several months. I do know that you can extend your stay by filing an I-539 form (
http://www.uscis.gov/portal/site/uscis/menuitem.5af9bb95919f35e66f614176543f6d1a/?vgnextoid=94d12c1a6855d010VgnVCM10000048f3d6a1RCRD&vgnextchannel=db029c7755cb9010VgnVCM10000045f3d6a1RCRD)
Your best bet is to call US immigration and Homeland Security and discuss it with them in detail. I have always found them very polite and helpful.
Good Luck