VISA questions….

sha.quan

VISA questions…. is there anyone can help?
I was previously with a German student VISA for language learning valid till 26 Nov 2009, but I got back to Taiwan at the end of Oct. right now I am in Taiwan and with a return ticket, Taiwan to Germany.

With the journey back to Germany with the single return ticket?
I will have an interview in Germany at the middle of Dec. if I apply for a German tourist VISA and take the single return ticket back to Germany, will I get problems from the German authority? Do I need to buy another single ticket, Germany to Taiwan? Or, I need to apply for a student VISA again?

Changing to working VISA from tourist VISA vs from student VISA?
Can a tourist VISA change to a working VISA in Germany? Or, I need to wait for the working VISA in Taiwan? Or, it will be easier to change to working VISA from student VISA (a student VISA for language learning)?