Twrp gives you the ability to make complete system backups in case something goes wrong and also flash modifications to the system and access your file system. It is a custom recovery. To me, i dont have root if i dont have twrp. Twrp also gives you the ability to flash custom software such as the roms listed above which removes bloatware, gives you a more updated cleaner and/or more customizable version of android without the lg/samsung/etc skin. So your device becomes closer to stock android as it was meant to be.. i highly suggest it for this device especially, but definitely FOLLOW ALL INSTRUCTIONS closely and as soon as you flash twrp make a backup immediately. Also, format your sd back to portable before doing this.
It seems ur interested in this and the only way to learn is trial and error, google and read read read. Plus a little common sense. People will help you out but theyre are also not responsible for ur choice, mistakes or device.