Do we really have to apply in person or we can send it through post?

The embassy does not accept the mail application. If you cannot go in person, you are suggested to apply through a local tour agency.

The fee is 1100THB for single entry type, 1650THB for double entries, 2200THB for mutiple entries valid for half a year, 3300THB for mutiple entries valid for one year. If you apply through an agency, they may charge service fee.

May I know your visiting purpose to China? The requirements are different for different purposes.

I will be transiting to Wuhan and have to stay there for 14 hours and so im thinking of going around the city for a little bit since i have a lot of time. Thank u

You mean you just make a international flights' transfer in Wuhan and want to tour around?
If so, you do not neee to apply any visa since the stopover is just 14 hours. You just need to apply for a stay permit in the airport to leave.