It could scare them. Beerus is a powerful and unpredictable god. The GT characters, who are used to their own challenges, would now have to deal with him. For example, if he decides to test their strength like he did with Goku in the regular series, they might not be able to handle it well.
Yes, in 'echo 3 true story', 'echo 3' is likely related to the 'true story'. It could be the name or identifier for the events that make up the true story.
It's hard to give a definite answer. Different comic universes and storylines handle the inclusion of Echo differently. You might want to check popular comic franchises or search online for more detailed information.
In most comic versions, Echo isn't deaf. However, there might be alternate or special story arcs where this could potentially be a trait, but it's not a common characteristic.
Sure, Echo is portrayed as deaf in the comics. This trait plays a role in shaping her personality and the challenges she faces throughout the comic series.