One question regarding mixing... I am thinking it maybe better to mix and keep in folded gloss magazine paper. I am just worried about mixing in a bag as I've seen some compounds such as etizolam seem to stick to the bag like some kind of electrostatic force is going on.
Try to find a better source of lactose - you do need the form used in health/pharm products. This is because it needs to be the refined granular form (you might get a more amorphous powder). I think you would be better using a small bowl-like container than folded paper. Essentially you're trying to replicate shear mixing. The baggies work fine (but doubled for potential splitting), but I hear you about electrostatic actives. However, I would think adding the first excipient dilution would reduce that issue.