Loadiine gx2 runs like any other loadiine, or even easier actually, you have two options, either loadi it directly from the host like previous versions, but it would be slower to launch since the elf loader with GX2 is about 3mb now, or use the SD package, which in that case you need to put the loadiinegx elf file in SD card (all explained in that thread), and this way you run it faster.
What I mean by Loadiine GX2 being eiser is it actually containes the kexploit inside it, so u don't need to run kexploit separately, just launch the loadiine GX2 twice first time. The other thing is, the same package works for both 5.3.2 and 5.4.0 so people don't need to compile separately for 5.4.0 anymore.
About your smash bros U, to install updates use wup installer. To buy dlc use nnu patcher to access eshop I guess?