Who is Shaitan? Is he same as iblis? Was shaitan or iblis an angel before ? Who is the king of hell or ruler of hell? Is hell a place to get punished for our sins? If yes then who is the punisher. If its not Allah then the punisher is an angel or iblis himself. If the punisher is just punishing us for our sins how does hell is bad place. Is Devil a punisher if yes then how can it be evil. What or who is evil?
By reading your question I am lead to conclude that you have very poor knowledge about Islam.
Iblis is the former name of Satan ( the devil ) .
Iblis belongs to the race of the Jinn ( made of smokeless Fire ; blessed with strength of the body ) . So he is NOT an angel. But in his prime time he was allowed to be in the company of the angels because he was the most devout worshipper of Allah.
Iblis later disobeyed Allah , and as a punishment he was kicked out of his high rank among the angels.He was renamed as Satan. He sought vengeance - to cause man to disobey Allah and send Man to hell. When the world ends he himself will be sent to hell ( because he disobeyed Allah ) and will be punished.
To Allah belongs the dominion of the Earth , Heaven and all that is between.
To ALLAH belongs the Kingdom ( the Universe, Hell, Heaven and many other things ). He is Al Malik : the KING ; King of Kings : The ruler of the all that exists and to him belongs all power and might.
Hell is indeed a bad place, the worst place you can end up in .You are punished their for your disobedience and arrogance. The Guardian of Hell is Malik ( an angel ) , so I do assume that their are angels in hell who are punishing the disbelievers ( on Allah's command ) .
You ask me whether Satan is evil : I believe there is no room for doubt here - ARE YOU asking whether one who tricks you into disobedience and cause you to go to hell is evil ? OF COURSE.