AFAIK, nobody has figured out the structure of the inventory files enough in BD to allow the addition or modification of items. I have not tried, since the main need for adding items is lost quest items, which can more easily be replaced by file swapping.

I never thought to try to change secondary stats directly. There is a mushroom that can give your characters a luck bonus, so there must be a base value of that stat, at least. It should be possible to edit Luck (if I have time in the next few days, I'll take a look at it). Initiative and accuracy, etc may have a base value somewhere, or could be calculated just from stats, skills and equipment (and be updated whenever any of these are changed).