About to install Nethunter on OP3 but still have some questions.

Well I use my oneplus 3 as my daily phone but I want Nethunter on it as well. Now I am still left with some questions.
such as:
What will it do with my battery life?
Will I still be able to use 'normal' apps (such as Whatsapp, Youtube, some games)?

Thanks in advance!

1) Nothing unless you start running the apps just like other apps.
2) Of course :) It's not a different ROM, it's just a set of tools with a rootfs (if you chose to get one) that will make it that you'll be able to run any Linux app on your phone.