I can't answer all your questions, but as to the ppm, it is the total. For instance, you start at 10 ppm, at enough calmag to get your meter to register 250-300 ppm (of which, everything but 10 is your calmag so far) then add your nutrients. After wards, your meter should read 800 or whatever (250-300 composed of calmag, 10 from your water beforehand, and the remainder of nutrients.

Also, the very last thing you want to do is pH check. Adding nutrients and other chemicals changes the pH, so fixing pH in the intermediate steps is a waste of time and a waste of chemicals. Do it last, and keep it between 5.8-6.2.

I also hear that some nutrients take up at different pHs than others, so some growers like to have a little variability in their pH, staying within 5.8-6.2. This I'm not as sure on, so don't quote me. I'm sure somebody with more experience knows better.