working hrs, process of application, etc

hi. i would like to add some more questions..
i think i might land in bankok on the 1st of June around 1300. if i make the straight trip to the embassy from the airport, will it be possible to apply within your working hours of the day? and what would be the expanse?

also, is it also possible to apply for mutiple tourist type instead of single? please refer to the following original texts if neccessary.
cheers
=================original txt==================
Hi.
I am south korean currently traveling in yunnan. i have 90 days single travelers type and i extended by 30 days. but i wish to stay another 3 months since i would like to discover chinese minority dance/music culture which i found unique and interesting. 

i would most likely not study in an intitution but travelimg around and observe the way the culture works. In this case. is it possible to renew it in the chinese embbassy in Bankok. if then what are the required documents?

lookin foward to ur kind answer. thank u so much :)