#2 - Is all of this part of a mod I could download? If not, can I simply add the entries to the bottom of the correct raw files?
Not a released mod, I created it for my personal use. My game is a compilation of several mods (including Dig Deeper, Rysith's Orcs, Age of Heroes, and recently the Murlocs) with many things stripped out and slimmed from there, but the only original modding I did myself were those conversions. In fact, they were my first real attempt at modding.
I mean, I could release my game mod as a simple "mod compilation" which includes mine, but I'm not quite done yet. I haven't played Dwarf Fortress in over a month because I use every spare minute that I don't have internet access to continue slimming down the mod, checking for repeats and bad tags, making lists to organize, figuring out what the heck Nodachis and Kettle Helmets are (two-handed katana-ish swords and those shallow WW1 helmets). After I finish the entity files, I'll still need extensive playtesting for myself to see how often it crashes, if there's too much overload, if the murlocs kill everything too easily, if anything's unbalanced like material values or weapon damage.
And then, when it's finally to a playable quality, I'll release it and the next DF version will be out, rendering most of my work fruitless. The end.