Translation Exercise Unit 1 - Part 1 [Basic Spoken Chinese Practice Essentials]
Your translations are basically correct, the only improvement I can talk about is to show the present continuous tense


  Where is Ke Leien going?


Can be translated to


  Kē Léi'ēn yao qu na?


And the second one


  I'm going to the cafeteria. How about you?


Can be translated to


  Wǒ yao qù shítáng. Nǐ ne?


And the third one


  Wang Jingsheng is going back to the dorm.


Can be translated to


  Wáng Jīngshēng yao huí sùshè.


And the fourth one


  Ke Leien is going to take care of some things.


Can be translated to


  Kē Léi'ēn yao qù bàn yìdiǎnr shìr.


Lastly


  You're going to the library, I also am going to the library.


Can be translated to


  Nǐ yao qù túshūguǎn. Wǒ yě yao qù.


By the way, how did you type pinyin with tune on it?