Best to mix nutes on an as-needed basis. They don't keep for more than a day or so before degrading the chemicals and the ph. If mixing for seedlings or rooted clones, I'll mix half a gallon, feed what needs to be fed, and use the rest on houseplants.
Overkill with regards to the soil combo's. Would pick a brand of soil, and stick with it. Diferent companies add different shit to their mix, and can ovedose the plants if mixed together. (extreme case, but something to watch out for) Having different mixes makes troubleshooting a bitch, too.
I'd stick with either the Fox Farms, or Miracle Grow...and the perlite. All the other stuff is really unnecessary, unless re-using your soils.
With the MG Organic Choice, remember...most organic ammendments and additives are slow-release. (road kill, calcium...) Don't overcompensate or freak-out if plants are a tad slower in getting the nutes. For the first three weeks to a month, compensate for the organic nutes already in the soil mix, by cutting-back on dilution strength of your Fox Farms nutes.
Don't forget to check-out the FF schedules, and your other post.
