New to Note 4 - Boot Loader / Root Confusion

I just picked up my Note 4 and have not even turned it on yet.
I have a few questions after reading various multi-page threads that i am unclear on.

I was looking at the threads and see that ChainFire is what to use to root.
http://forum.xda-developers.com/note...-root-t2897428
It states that Stock Recovery is installed, does this mean that I can use that recovery to flash TWRP or will i have to use ODIN for that?
What version of ODIN needs to be used?

Is there any version of Root that does not trip KNOX?

I am confused about the different boot loaders / Broadbands (basebands?).
How do I find out what boot loader / Broadband i am on?

I am reading a lot of reports that 5.x is giving very poor battery life. Is that the Case Still?

Thanks for any help Ya'll can give.