Is it going to somehow delete my normal kernel? Or just add to it?
Depends on your Distribution. From your package syntax i presume you are using some Ubuntu Derivate. They don't delete your default kernel unless you explicitly ask for it. So yes, they add a new kernel you can choose to boot from.
Also, do I really need it?
Depends on what you need and want to do
What does it do?
Ubuntu themselves explains it like this:
These are some simple guidelines provided to help you understand which kernel, and in which order, you should test to fit your use case.
- If you do not require low latency for your system then please use the -generic kernel.
- If you need a low latency system (e.g. for recording audio) then please use the -preempt kernel as a first choice. This reduces latency but doesn't sacrifice power saving features. It is available only for 64 bit systems (also called amd64).
- If the -preempt kernel does not provide enough low latency for your needs (or you have an 32 bit system) then you should try the -lowlatency kernel.
- If the -lowlatency kernel isn't enough then you should try the -rt kernel
- If the -rt kernel isn't enough stable for you then you should try the -realtime kernel
Ubuntu makes it really easy for you to try those kernels. Just install them and experiment a little which ones fit you most.
What would I loose from my standard kernel?
Mostly Power Saving features.
Somehow I think I've heard something about the normal kernel being good enough already.
For most end user situations that's true. But if you need professional latency for let's say video editing where every single frame is essential, then you should try the other kernels.
