Canadian living in Guatemala

I am planning to visit China for business reasons in August. Can all the documents be completed from Guatemala, or do I need to appear in person in Costa Rica?
Will in need a letter from one or more of the factories I plan in visit in the Shanghai area?
Do I need to have my airline reservations paid for and confirmed before applying for a visa?
Do you need hotel reservations confirmed also?
What will be the fee in dollars, and how can I pay it from Guatemala (wire transfer, DHL or ????)
Thank you