Is shaitan created with the same freewill as humans? How do they reproduce and how do they look like? Are there any hadiths on these?

Yes Shaitan is a Jinn, and the Jinn have free will.
In a very long narration narrated by our sixth Imam (as), Allah the almighty agrees to give Shaitan two offspring for every one Adam (as) has. As for his appearance, I have never read any descriptions about this, I am unaware if there are any present. But I have not found any.