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.
Sasuke would probably be initially skeptical. He might think that Naruto is relying too much on an external weapon instead of his own natural abilities. However, he would also be intrigued and might keep an eye on Naruto to see how he uses it. Sakura would be worried. She would constantly remind Naruto about the dangers of the gun and how it's not a traditional ninja weapon. She might even try to convince him to get rid of it.
In most 'Naruto gets sick' fanfics, his friends are very concerned. For example, Sakura will immediately start using her medical skills to diagnose and treat him. Sasuke, although he may not show it outwardly as much, will stay by Naruto's side and keep a watchful eye. Shikamaru might come up with plans to make Naruto more comfortable during his illness. And Hinata, she would be really worried and would probably bring Naruto some home - cooked food to help him regain his strength.
His friends would most likely rally around him. Kiba might use his dog Akamaru to scout the area and make sure there are no other immediate threats. Hinata would be really worried and would try to use her Byakugan to see if there are any hidden enemies or if Naruto has any internal injuries. Choji would offer some of his food to Naruto to give him strength, as his clan's food can have special effects on a ninja's body.
I think his friends' reactions would be mixed. Kakashi would be that calm and collected presence, giving Naruto some words of wisdom about this new chapter in his life. Hinata might be a bit sad at first because she had feelings for Naruto, but she would also be happy for him. The rest of the Konoha 11 would be excited. They would see it as an opportunity for Naruto to bring about new changes not just in Konoha but in the whole ninja world. They would all gather around to support Naruto and make sure the marriage goes smoothly.
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.
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.
Naruto would probably be very excited and want to immediately start making changes for the better. He has always been about hope and improvement.
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.
Well, Naruto's friends would be in an uproar. Iruka, who has always been like a father figure to Naruto, would be heartbroken and would not rest until he knew Naruto was safe. The other Konoha ninja would also be affected. Neji, despite his initial coldness towards Naruto, has come to respect him. He would see Orochimaru's actions as a threat to the village and to his friend. Tenten would offer her weapon - related skills to help in any rescue attempt. And Hinata, who has deep feelings for Naruto, would be extremely distraught. She might even try to take on Orochimaru herself in a desperate attempt to save Naruto, regardless of the danger to her own life.