The Avengers might be initially shocked. For example, Iron Man could start by using his technology to find ways to help Hawkeye communicate better within the team. He might create special devices for him.
Black Widow, being Hawkeye's close friend, would be very protective. She might already have some idea about his condition and be helping him secretly. When the others find out, she could be the one to educate them about how Hawkeye has been coping all this time and how they can all support him better.
They would need to make some adjustments. For communication during missions, they might rely more on visual cues. Hawkeye, with his excellent archery skills, could use his own set of signals to indicate things to the team.
Tony Stark would likely find it hilarious. He'd probably be the first one to start making jokes about it. He might say 'Oh, Hawkeye, you've got some really creative fans out there. I should hire them to write my memoirs!'. As for Hulk, he probably wouldn't care much. He might just grunt and go about his business. But if he did read some, he might not understand it very well and get frustrated. Hawkeye himself would probably be embarrassed at first, but then he'd start to see the humor in it and might even enjoy some of the more positive fanfiction about him.
Well, some of them might be really surprised. Tony, for example, would probably crack a lot of jokes about Steve being young. He might say things like 'Cap, you were this cute little thing?' Natasha, on the other hand, would be more observant and start thinking about how this new information could be used in future strategies. Thor would probably just laugh heartily and pat Steve on the back, saying something like 'Tis an interesting discovery, young Steve!'
On the other hand, if some of the fanfiction was a bit too outlandish or inappropriate, it could make things a bit awkward. Hawkeye might feel embarrassed, and the other Avengers might not know how to react. But they'd probably try to smooth things over and remind Hawkeye that it's just the creativity of the fans and not a true representation. They'd still support him as a teammate.
The Avengers would likely be overjoyed. Tony might crack a joke about Coulson's 'resurrection' while also being secretly relieved. Steve would probably be very happy to see his friend again. Natasha might be a bit more reserved in her reaction but still glad. Thor would see it as a great sign and welcome Coulson back heartily.
The Avengers would be furious. Natasha would use her spy skills to find out all about the bullies without them even knowing. Thor might be a bit more direct, perhaps showing up at the school in his full Asgardian glory to scare the bullies straight. Clint could offer to teach Peter some self - defense moves so he can stand up for himself.
Tony Stark would probably be both proud and a bit worried. Proud because Peter is this brilliant young mind who has managed to be a hero on his own, but worried because he's just a kid. He might start to hover over Peter more, offering him better tech and trying to mentor him more closely. Captain America would likely be very accepting. He sees the good in people and would be happy to have another brave soul on the team. He'd probably offer Peter some words of wisdom about using his powers responsibly. Thor might be a bit clueless at first. He doesn't quite understand the whole 'secret identity' thing as well as the others, but once he gets it, he'd be all for having Peter around. He might see Peter as a little warrior and be eager to train him in his own Asgardian ways.
Some Avengers might be protective. For instance, Captain America could immediately start giving Peter advice on how to better handle his dual identity and keep himself safe. He might offer training sessions to help Peter improve his skills as Spider - Man.
In this fanfiction, the Avengers would likely be filled with shock. They might stand there in stunned silence, unable to process what just happened. Their expressions would range from horror to disbelief as they watched their friends and allies turn to dust.
In this fanfiction, some Avengers might be in shock. For example, Captain America could be deeply saddened, his belief in justice and protecting the world shaken. He might feel a sense of failure for not being able to prevent the Snap.