How should I present data written in another language? I'm writing a research paper in English but the topic is about a different country and the data is written in a different language, Arabic.

Should I translate the data into English?
If yes, should I include a version of the excerpt in the original language?
If yes, how?

Apart from using excerpts of data, I sometimes have to mention certain words of the original language such names of participants and research fields, but I do not know whether I should use transliteration, translation or both.

Thank you
It would depend how much your translation of the story makes a difference to your thesis. If it doesn't particularly matter with respect to the finer details, it would be sufficient to provide the entire story in Arabic and then give a synopsis in English. If it's more critical that the audience knows what each line means, then give each sentence with its English gloss. 

If you wanted to go to the extreme, you would have an interlinear gloss, which means that each word, or even morpheme, is glossed individually, and then a free translation given at the end. Here's a Hungarian example (from the Leipzig glossing rules):

Gila abur-u-n      ferma  hamišaluǧ  güǧüna  amuq’-da-č. 
now  they-OBL-GEN  farm   forever    behind  stay-FUT-NEG 
‘Now their farm will not stay behind forever.’ 


In linguistics we use these literally hundreds of times in a thesis, because this is where our data really is. It's probably more depth than you'd be willing to go into, and I would advise against it unless the Arabic syntactic and morphological features are absolutely critical to your thesis. The conventions that most linguists use (and tweak to their own subject language) with respect to the names of various grammatical features (OBL and GEN, for example) can be found in the Leipzig Glossing Rules.

I think you'd be fine to select from either giving the entire story followed by a synopsis of whatever detail you'd prefer, or a line-by-line transliteration.