[RadioKid]

Apart from existing discussion, let me check the original Japanese in Romaji.

Daigakusei Desu ka ? :
Student is usually trnaslated as "GAKUSEI". Dai-Gakusei is an univercity Sutudent.

Nanji ni shuushin shimasuka :
Shuushin (就寝) is not used in casual communication.
"Nanji ni ne-masuka" or "Neru nowa nanji desuka" would be natural.

Nanji ni kishou shimasuka :
Kishou (起床) is not used in casual communication.
"Nanji ni oki-masuka" or "Okiru nowa nanji desuka" would be natural.

Hai :
Note that "hai" does not always mean "yes". "Hai" strictly means "I agree you" or "I'm listening to you". Do not trust Japanese people when you ask a question in negative form.

Nankai :
This does not make sense. "dore kurai?" or "dono kurai?" would be better.

Supo-tsu Kuruba ikura desu ka :
"Supo-tsu Kurabu ha ikura desuka" or "kaihi ha ikura desuka" would be better.

Ichi ka getsu :
"Ikka-getsu" is used usually.

Eigyoujikan wan an desuka :
"nan desu ka" is too vague.
"Eigyoujikan wa nan-ji kara nan-ji made desuka" is accurate. usually, "Eigyoujikan wa?" will do.

Ikunichi :
does not make sense. I do not understand what do you want to ask by "what days?". If you are asking day of week, "nan you-bi ni?" will do.

Irashaimase :
"Irasshai-mase"

Menyu wo miru kotogadekiru ka :
this is too rude. it is "Menyu wo miru kotoga demasu ka" in polite form.
"Menyu wo mise-te kudasai" will do.

Sushi wo matte imasu ka :
"matte" is wrong. "motte" is correct.
SUshi wa ari-masu ka is usually used.
"How much does it cost?" should be "ikura desu ka".

Iie, sumimasen. Keredomo Tempura ha oishiidesu :
"Iie, sumimasen" is OK as itself. However "keredomo" is not used in such way.
"Iie sushi ha gozaimasen. Sumimasen-keredomo, Tenpura wa ikaga desuka?"
"ga" instead of "keredomo" would be better in casual form.

Sore wa kyu-hyaku en no hiyou ga kakari masu :
"Tenpura ha kyu-hyaku en desu."

Domo Arigato. Oishikatta desu :
It is ok, "Gochisou sama deshita" would be short.