what is H1b visa?

feel frustrated for this 0-level question :( I did some web search but could not get answers for below questions)

new to H1b visa, company filed application for me and got approved. several questions as below, much appreciate for any input:
1, is there an 'visa' to be issued? or just a paper of 'approval notice'?
2, is there an 'EAD' card to be issued?
3, now in the US, if planning to go back China after Oct. 1, do I have to make an appointment with US consulate and get a return visa? What should I have to take with me when interviewing? (paychecks, approval notice, contract with the company?...)
4, if needed, how could I get this visa in the US (better before I leave US), instead of in China? really pain to make appointment with US consulate in China, and long time waiting, and chances to be rejected...
5,how much it costs? if needed.
6, how much it costs for renewal after 3 years? (to renew another 3 years).

thanks very much in advance,

~aoe