What would be the best tool to install (and how do i install and set it up) to get the most out of laptop battery and heat wise? Is it the laptop-mode-tools??
Thanks 
Yeah I would recommend laptop-mode-tools. But this needs most of the time configuration for your hardware.
Therefor I would first recommend using the Intel powertop tool which shows you how many watts every chip on your device uses and how to save more powert. It is a console based app so that you need to start it from terminal after you installed it.
Ok, Thanks!
Laptop-mode-tools is installed and configured by default in Netrunner Rolling / Manjaro.
I would suggest however you can optionally try out LTP instead of laptop-mode-tools and see if these are better for your system:
https://wiki.archlinux.org/index.php/TLP
PS. LMT is to be depreciated soon and LTP is scheduled to replace it.
Ok,
So should i first uninstall laptop-mode-tools? then install tlp?
That depends, LMT is not depreciated by Manjaro / Netrunner yet, so unless you are having issues with heat or battery life, I’d say leave well enough alone.
If you are having issues, then yes remove LMT first and then Install / configure LTP:
Not officially supported by Arch (available in the AUR and in the Manjaro repository):
https://wiki.archlinux.org/index.php/Laptop_Mode_Tools
officially supported by Arch (provided in the offical repositories):
https://wiki.archlinux.org/index.php/TLP
looking at both wiki’s you can clearly see how much easier TLP is to use.
great thanks!