Just a couple notes.

you don't need the watashi ha in the second sentence. It is always assume that you are the subject.
Also, when you're talking about a topic, it's better to use the -tain desu ending. (kakitai~n desu)

Lastly, before a comma, you should get used to the -te form, as it flows slightly better,
nihongo wo benkyou shite, dare mo benkyou shimasuka?

Thanks for the suggestions. I am familiar with te form, just didn't know that i was supposed to do that. Also, it's really hard for me to read Japanese in roumaji, it just looks so weird!

haha yeah I know, I hate romaji too.

But yeah, there are a lot of weird rules, one of the quirky ones is 'don't have a dictionary form of a word twice in one sentence'. There are like a dozen ways to mitigate multiple verbs haha. It can be very confusing.

残念ですね…私も大学で日本語を勉強しています。二度日本に行った。

そうですか。日本で何をしましたか。

arubaito de nihon no wakamono to issho ni shigoto wo shite iru. Kare ha totemo subayaku hanasu. etooou, rikai suru koto ha hijou ni muzukashii.

Ni Hou

我也学习汉语！可是这里我要练习日语。

行旅する。東京や京都や金沢市を見った。

東京と京都と、どちらの方が好きですか。