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.
He would probably be very angry. Naruto has always been a free - spirited person, and being experimented on against his will would be a huge violation of his rights. He might initially try to resist physically, but as the situation gets more complex, he could start to plot his escape and revenge.
He probably resists. Naruto has always been a fighter. He would not just sit there and let them experiment on him without a fight. He might use his basic ninja skills like substitution jutsu to try and escape the experimenters.
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.
Sakura might be extremely angry and feel guilty for not being able to protect Naruto. She could immediately start planning ways to rescue him and make Danzo pay for what he's done.
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.
Tsunade would probably be very suspicious at first. Naruto suddenly appearing from the future? It's not something that happens every day. She might think it's some kind of enemy's trick or a genjutsu.
He would probably be very confused at first. Naruto has always trusted Tsunade, so the betrayal would come as a huge shock.
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.