The fountainhead of ABC pyro knowledge is Michael Smith @ http://www.michaelandpaula.com. If you get your chemicals at http://www.arcraftchemicals.com you can talk to Mike Jacobson, who is very familiar with Michael Smith's formulae and will make you a kit of chemicals in the right proportions.
It does not make any difference in which order you put in the solutions as long as the carbonate (solution C) does not come into contact with the pyro (solution A) until you're ready to begin development.
The correct proportions for normal or N+ development are 1:1:1:7. For negatives of scenes with "extreme contrast" (Michael's words, not mine) use 2:1:1:15.
BTW, the term "pyrogallic acid" is a misnomer. Pyrogallol is a phenol, not an acid. That's why it's so easily absorbed through the skin. There is a phase it goes through during manufacture where it is pyrogallic acid for a while but then it's transformed into pyrogallol.