Question about certain game mechanics

Hi, I was hoping someone could link me to a source of some general game mechanics, specifically how damage calculations work.

For example if a gun has +50% weapon damage is that an implicit modifier to the gun itself or is it globally affecting all weapon damage multipliers. Also which modifiers are multplicative and which are additive. Same thing for damage reduction.

I also am wondering if damage over time effects, like from a maliwan weapon can stack or if the dot just refreshes each time its applied. Also is there some base duration for damage over time effects.

Lastly I cant seem to find a test dummy anywhere in sanctuary like there was in bl2. And a dummy would allow me to test alot of things myself…

The test station on sanctuary 3 is in the shooting range in Marcus’s area I’m not sure if it has an actual test dummy though.

To my knowledge through observations, DOTS can stack, rather than just refreshing the proc.

I assume weapon damage is just (all other damage calculations) x (1.50 weapon damage).

Which are additive and multiplicative, I do not know.

Well looking around more it seems like there is no test dummy in this game (which is really annoying), so there doesn’t seem to be any efficient way to test dps unlike bl2. Also I haven’t seen a clear answer on what damage modifiers stack and which are multiplicative, (also kind of a big deal). Hopefully someone can answer these questions.