To visit a trade show in China Do i need a tourist visa or a business visa ?

Answer 1

Visiting a trade show is a lesiure activity unless your company requires you to do so. Yes, you would need a visa depending personal or business.

Answer 2

If you sent by your company, you will need a business visa.

Answer 3

You may go on a tourist visa unless the conference admins send you a special invitation document that will allow you to come on a F visa.  

L (tourist) visa is fine.