I'm not familiar w this series...few questions...

In comic books they are formed by Star Lord to defend the Kree empire. In MCU they are formed to fight against a Kree warlord. So in MCU you can think "Guardians of the Galaxy" as the name of a mercenary outfit.

We are talking about a genetically mortified alien raccoon, so of course he can speak English.

It is an American movie, so all aliens speak English, that includes trees.

If you ask why Groot can hear without ears, then clearly you have issues.

You are going to watch a comic book movie, so thinking does not help at all.

If you have further questions, then maybe you shouldn't watch this movie.

1: This galaxy. We know because there's a scene on Earth, and a raccoon.

2: Varied species, and I believe they're all drawn from varied Marvel comics, which tended to have a lot of aliens that looked like humans with weird skin colors.

3: It's just a fun movie, dude.

4: If Groot can grow appendages hundreds of feet long in a few seconds, presumably he can grow vocal cords.

5: I presume all anatomically normal raccoons have vocal cords, they make various sounds. So presumably whoever modified Rocket modified his vocal cords to sound more like an adult human male, which only leaves the question of how a raccoon is able to mimic human speech without lips. How's he making "B" and "P" sounds, then?

6: A comic-book nerd might know.