I am planning to get H-1B visa stampe in Shanghai. Could anyone advise what's the procedure for that? do I have to call to make an appointment for interview ahead of time? how long they normally schedule for? what's the forms I need to fill out? DS-156, 157 and 158? I notice those forms are for nonimmigration visa, but H-1B is immigration visa? I changed my status from F-1 to H-1 in USA, so I will need a visa stamp to come back. How long I normally get the visa stamp? what if run the security check? If security check take too long, can I withdraw my application for H-1B visa stamp? and come back on Advance Parole instead? I do have valid Advance Parole in hand, but want to keep my H-1 status.
Sorry for so many questions. and I appreciate any answers.