To get a multiple entries tourist visa is possible, you can just require for 6 months one to your application form, providing your prrof that you need to visit China for many times during this period. The general processing time at Chinese embassy is 4 working days. You can not apply China visa online, mail service is not appliable as well. If you can not go to Chinese embassy in person, you can entrust others or travel agency to handle it on your behalf.