That tutorial is outdated. This one
is much more up to date and makes for much better lipsynching.
As for the file names, I find following the game's system just makes for really long names. Usually I name it in accordance to the character and the general area they're in, so for your mod I'd do something like tar03_gadon01, tar03_gadon02, etc. (Though you might want to do something more specific to avoid conflict, maybe use the initials of your username as a prefix so it'd be mgf_tar03_gad01).
And in my experience you can just stick your custom voice overs in the StreamWaves folder and they'll work (put your .LIP files in the Override).