Minecraft GommeHD Developer?

I'm considering applying as a developer at Gommehd, but before that I have a few questions (I think I can, but I don't know the terms). First:

What does asynchronous and thread-safe mean (or what will I do)?
What does design patterns mean (are these the formal rules in Java [eg that a class starts with a capital letter?])
Is Git and Maven really that important (and what exactly do they do)

If you can't read it yourself then just leave it.

Asynchronous: Working with threads / coroutines (in Kotlin)

Thread safe: see synchronized and volatile

Design Pattern: Something like Singleton Pattern, but more about it https://dev-tek.de/lexicon/entry/88-design-pattern-1-was-sind-die-design-patterns/

Git: Working on projects online so that several can work on them

Maven: So that you don't have to download the dependencies for everything, it does it automatically