The first three are fairly obvious, the boss field controls anything that is considered a boss by the game, so if a healthbar appears, this is the field that's applied. These control the weight in each category. On a bag-by-bag basis, in Lootbags_BagConfig.cfg under each bag there are four fields: You can change how often bags can drop one of two ways.
I use my own handling system for bag drops, so no other mod should be able to affect them unless it is especially coded to do so.