It’s hard to know how to answer your questions because they are so general. The atmosphere in the city is nice, nightlife is okay, part time jobs depend on your skill set, connections and how hungry you are for work. I would recommend renting an apartment over living in a dorm, but I’m not sure of the price difference, or what dorm costs are like at Sichuan University.
I know there are some other Moroccan expats in Chengdu, perhaps even a community of them?