Tsunade could be impressed by the power of the Kyuubi suit. Given her own strength, she would appreciate the additional boost it gives Naruto. She might even see it as a valuable asset in protecting the village and start to develop strategies around how Naruto can best use the suit in combat situations.
She could also be a bit motherly towards Naruto in this situation. Tsunade has a soft spot for the younger generation, especially those she cares about like Naruto. So she might fuss over him a bit, making sure he's taking proper care of himself while using the suit. For example, she could be concerned about the physical and mental strain the Kyuubi suit might put on Naruto and offer her medical expertise to help him manage it.
His friends' reactions would be intense. Kakashi, as Naruto's teacher, would feel responsible. He would gather as much information as he could about the kidnapping. His friends from Team 7 and the other ninja in the village would band together. They would know that Naruto is strong, but also that the Kyuubi is a powerful and dangerous force. They would not rest until they found Naruto. Some might be angry at the Kyuubi, while others would be more focused on just getting Naruto back safely. They might also try to find ways to communicate with the Kyuubi, if possible, to negotiate for Naruto's release.
He would probably also feel angry. After all, he has sacrificed so much for the village and for them. He might start to question his own beliefs and values. But Naruto being Naruto, he would not give up easily. He would try to prove his innocence and show them that they are wrong. He could go on a journey to find evidence or seek help from other allies who still believe in him, like Shikamaru or Kakashi.
Tsunade could be a bit flustered at first. After all, she is a tough - as - nails leader, and a hug from Naruto, who she has watched grow up, might make her feel a bit vulnerable in a good way. She might then relax and even give Naruto a pat on the back in return, showing her appreciation for the gesture.
Naruto could also become angry. He might feel betrayed by Tsunade and the village. This anger could fuel his determination to prove his innocence or worth. He could set out on a journey to become even stronger, so that one day he could return and show everyone that they were wrong to banish him. He might also start to question his own beliefs and values, which have been centered around the village and its people.
The other kages from different villages would also have reactions. Gaara, being Naruto's friend, would be happy for him and send a grand gift. The Raikage might be a bit surprised but would respect their decision. The Mizukage would probably see it as an interesting development in the relationships between the ninja villages. All in all, the reactions would range from shock to joy, but in the end, most would support the union.
At first, Naruto would probably be excited. He's always eager to get stronger, so he might see this as an opportunity. He'd trust Tsunade because she's the Hokage and a respected medical ninja. But if the experiments got too painful or started to seem strange, he'd start to question things. He might try to talk to Tsunade about it, but in his Naruto - like way, still be respectful.
One plot idea could be that Naruto, in his Kyuubi - enhanced suit, has to team up with Tsunade to face a new, powerful enemy that threatens the village. Maybe the enemy has a special ability that can only be countered by Naruto's Kyuubi powers and Tsunade's medical and combat skills combined.
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.
The Kyuubi suit might make her relationships more complex. Her friends could be both in awe and a bit scared of her new power. For example, Sasuke might be initially hesitant to approach her as he's not sure how to deal with the Kyuubi's influence. But over time, as he sees that she's still the same Naruto at heart, their relationship could strengthen.
She might be initially shocked. Given her own past traumas and her relationship with Naruto, she could be hesitant at first. But then, considering Naruto's lonely situation, she might warm up to the idea and show a more maternal side towards him.