Help with rooting Nexus 5+Install costume recovery topic

Hey guys i updated my device a while ago and now i have 5.0.1 version.

I don't have recovery and i dont have root access.

can someone please give me a guide how to install costume recovery again?

i'll install TWRP 2.0.8.1 recovery and then i'll root my device because now i can't.

thnaks for anyone who will help.

costume rom for the note 4, is it really necessary? topic

before i bought the note 4, i used to own S3.
while the base original rom for the S3 was pretty bad in most ways & custom roms were a must, it's not the case in the N4! i find it fast, no bugs or lags etc.
so i was wondering, when talking about the note 4, why bother with rooting and costume roms, losing the warranty etc?
what's the different from custom roms to Samsung's original rom?