His other friends like Shikamaru would be in shock. Shikamaru, who is usually calm and collected, would struggle to come to terms with Naruto's death. They would all have to deal with the loss of the village's hero and a great friend, and it would likely change the dynamics of the entire group.
Sakura might be initially shocked and a bit jealous at how cute Naruto - as - a - girl is. Sasuke would probably be confused at first but then act indifferent. Kakashi would be his usual calm self, but might crack a few jokes about Naruto's new look.
Sakura would be devastated. She had known Naruto for a long time and had come to care for him deeply. She might feel guilty for not being able to stop him. Sasuke would also be greatly affected. He and Naruto had a complex relationship. He might regret not being there for Naruto when he made the sacrifice. His friends from the village like Shikamaru and Choji would feel a great sense of loss. They would remember Naruto's always - positive attitude and feel that the village had lost a great light.
Shikamaru, being the intelligent one, would try to analyze the situation first. He would understand that Naruto isn't himself and would start to plan a way to reverse whatever happened. He might try to gather the other ninja to form a strategy. Kakashi would be deeply disappointed. He has trained Naruto and seen his growth, and this change would be like all his efforts going to waste. He would try to talk to Naruto, using their past experiences to try and break through to the real Naruto inside.
Sakura would probably be very angry at first. She'd likely try to find out the truth immediately and would not rest until she clears Naruto's name. She might use her medical ninjutsu skills to get into the jail if needed.
Naruto would probably be very excited and want to immediately start making changes for the better. He has always been about hope and improvement.
I think Naruto's friends would be quite shocked. For the more traditional ninja like Neji (if he were still alive in this fanfic), he would see the gun as an abomination to the ninja way. However, Naruto's closest friends like Kiba would be more open - minded. Kiba might see it as a cool new weapon and want to see what it can do. But overall, they would all be concerned about how Naruto got the gun and what it means for their world of ninjas.
As for Shikamaru, he would probably find the whole situation too troublesome. He might avoid 'female Naruto' at first, but then when he realizes it's really Naruto, he would start to give advice on how to handle the situation in the most efficient way, like how to avoid unwanted attention from other guys.
Sakura might be initially shocked as killing is a serious matter, but then she would understand Naruto's reasons if she saw the cruelty of the Celestial Dragons. She would support him in the end. Kakashi, on the other hand, would probably be more analytical. He would first assess if Naruto's actions were truly necessary and if there were any other ways to deal with the situation. But once he realizes the nature of the Celestial Dragons, he would back Naruto up.
Sakura might be initially shocked. But being a good friend, she would quickly try to understand what happened to Naruto. She could offer to help him find a way to change back or support him in dealing with the new form. Sasuke, on the other hand, might be more aloof at first. He would see Naruto's transformation as a sign of weakness, but as time passes and Naruto proves his strength in the new form, Sasuke might start to respect him again.
It would change it drastically. Naruto is known for his loyalty and friendship. If he were to kill his friends, it would shatter the image of the hero. His friends like Sasuke, Sakura, and Shikamaru are important to the overall story and relationships in the Naruto universe. Their deaths at Naruto's hands would create a huge rift among the other characters.