Dashlaunch is found in the NAND once installed...
To check version you can use the Dashlaunch installer, or Simple 360 NAND Flasher 1.4b for instance
Your edit is incorrect, Dashlaunch consists of 2 major parts;
1. There's "lhelper.xex" and "launch.xex" which are included in your nand, this handles booting stuff like FSD directly when booting the console, it also have alot of other features (as you can see in the launch.ini file)
2. There's the installer/configurator which is the graphical program you use to edit settings and/or install/upgrade Dashlaunch
The way to upgrade dashlaunch is just download the latest Dashlaunch package and run the installer, but... generally, when you want to upgrade dashlaunch you also want to upgrade your kernel, they pretty much go hand-in-hand, so... read a tutorial for updating your kernel, download the latest version of the NAND Builder and you usually get the latest dashlaunch aswell (xeBuild itself doesn't include dashlaunch unless you unpack those files, but if you use xeBuild GUI, JRunner, AutoGG etc. you'll have it included)