well...to determine all your quetions depends on what your importing.
your really should get a book or information from people in the business. the tax levied depends on what item is imported exactly. shipping charges depends on the method of shipment. airmail, shipmail, donkey mail. it varies greatly and is by teh pound usually. for example...DHL for 35 pounds is like $100+ from europe. Im nto sure what shippers service china. the shipping method will greatly depend on the factory too. they usually have one international shipper serving them. if they do large quantity shipments then it will be mostly by water. travel time is estimated 4~6 weeks. thats including customs check. and all anticipated delays.
you realky need to give more information if you want good advice. email me and I'll be willing to help you out even more.
john <jtang@jhu.edu>