Do I need to apply Visa-free Transit G !!!

Hi there,

I am a Vietnamese Passport holder, and I have a Schengen visa for student.

My question is, If I reserved an airplane ticket like this: Helsinki - Moscow - Shanghai - Bangkok but I have to pick up and recheck my luggage to Bangkok and transit in Shanghai 7 hours 45 min. Do I need to apply a Transit G? and also I want to go outside for a visit (approximately 4-5 hours).

If I have to apply for a visa-transit, where can I do (at the airport or at the embassy?) or can I apply for online application

Greatly appreciate any advices. Thanks a lot.