I totally agree with @Dankerson, organic growing looks simple on paper, but getting it really dialed can be tricky. I think the easiest way to start out is with mild soil or soil less mix and one of the standard bottled nutrient lines like GH, Fox Farm, FloraMax, Canna, they all work well when used properly and make understanding and controlling inputs easier. This is all just IMO of course.
I know youve already decided but just as a reference Ive ran OF and for my first two grows used their bottle nutes and I recommend them. They work great if used properly.
It's an excellent soil and their bottle nutes are pretty decent. I think because they are so popular a lot of new growers use them and end up blaming the soil for their mistakes. I've had great success with both planting all my autos straight into OF and using a 1/4 strength on their nutes. I averaged 3-6oz a plant, larger strains more.
Sounds like your set on the water front, have a gander at the tea lab stuff when you get a second. I wish I had before I started my grow as I would have likely gone that route.
Now that does make sense. Will definitely try it on my next grow!