101 first, I use oxalic acid from Florida laboratories which is 99.6% pure. You could also use Savogram wood bleach from a hardware store.
2) the standard dose is 1 gram per deep box, which would mean 2 grams for 2 deeps or 3 mediums. You could double that dose without any adverse effects on your bees. 2 grams= 1/2 teaspoon
3) some prefer to make the hole in the back rim of the bottom board, However I prefer to make the hole higher and on a 3 box hive I make the hole in the second box in the center of the frame rest as close to the edge as you can get it so that the vapor comes out between the upper and lower frames. Just see which way suits you best.
4) Once my honey comes off by late June I will do 5 treatments 5 days apart which will take 20 days, I will do this again in Mid August and then do single treatments in November and again in December and thats it until June next year. Mite checks on random hives by the State inspector yielded 0 mites on my apiary inspection on May 14 th 2019 so I treat each hive 12 times a year.
5) I treat all my hives (40 odd) on the same day, that is 3 yards and the treatment takes about a minute a hive. I hope this helps .