Alright, so hear me out...

I want to write songs. Now for me, I have a metal band that I'm in and i've got a routine down for writing songs for that, but I want to start something new. I love Nine Inch Nails a lot and I want to sing. For the band I'm in, I only do guitar. I want to start my own "Nine Inch Nails", if you will. In a sense that Trent makes his own music and his own lyrics, it's all him and all his music. Also, I don't wan to make metal, I want to make the same type of music Trent does. So regarding that, I have some questions..

To be frank, I have no idea how to write a song like that. How to make the beats, write the lyrics. I really want to make songs that are like Nine Inch Nails. Don't get me wrong, I want my own sound, but I really like what Nine Inch Nails has done because it's so different from everything else. I want to know how the writing process should go, how do lyrics get that deep and flow so well, how do the lyrics and music fall in line in such a unique and beautiful way? Basically I want to learn what Trent does but make my own music with his methods. I don't know if I want to sound like him or not, to be honest I'm really confused at to what I want right now, but I know I really want to make that "kind" of music and I have no idea how to go about it, so help would be appreciated. Thanks.
Also, one more thing, I remember very few lines of him talking about when he talks about how he writes his music. Now I want to know, when he says music, does he means the actual music, or the lyrics? Which does he write first? If you write the music first or vice-versa, how does that go and which does Trent do? Thanks again.
Well, as far as the order of lyrics/music first, don't base it off of what trent does. One may not work for the other, and certainly doesn't get the same results. The topic of order is a long standing one, but generally, music first is easier. If you write a set of lyrics that STRICTLY adhere to meter and rhythm, then you can do that first, especially if your song is bare bones (which trent does plenty of times, if I remember correctly). As far as beats, which I have little knowledge on, I guess you could transpose stuff from guitar, but that might not always work. I'd say start off with a melody, put some percussion or bass to it (to make the basic rhythm) and then add the rest. I have no idea where you'd get the sounds and beeps that he uses, so let someone esle help you with that.