mobile

First off, I'm a total newbie when it comes to anything Samsung. I've never owned a non-AOSP device.

So that being said, GS6 is in hand and I really do like it. Basically I only have a couple issues, biggest one being I really want some of the touchwiz bloat gone, I want a navbar and the physical buttons disabled, AOSP dialer/contacts. I know a lot of these things will be able to be done with root, but to be on the safe side I would prefer not to root. So my question is very simply:

Flashing custom touchwiz roms, will that void warranty, trip knox, require root?

I know there might not be an answer for the S6 but for other Samsung devices, hopefully the S6 will be similar.

Thanks in advance.