rule of thumb: dots that say 'deal X damage over Y seconds' snapshot; the ones that read 'deal X damage every Y seconds' update on every tick. not always true because of the zenimax:tm: factor but most of the time it is.

So for example the base tooltip on soul trap is calculated at the moment of the cast (actually when it lands because of it's a projectile but thats another thing), based on your weapon/spell damage and stamina/magicka on that bar at that moment. Blockade on the other hand checks your stats every 1s for the tick base tooltip.

Then the base tooltip is updated every second in both cases depending on your % damage done, penetration, crit damage, crit %, etc.

So if you cast soul trap on your back bar then switch to your front bar with camo hunter and proc minor berserk, your soul trap will have +5% damage done and +10% crit.

it does proc the backbar glyph, yes, but that is the only thing that 'carries over' to the other bar, with the weapon sets. Volley, blade cloak, and i believe stampede also work the same way, where they will proc your backbar glyph through bar swap, the same way master's bow increase your weapon damage even if you're on the other bar. (poison injection does not proc the glyph though, as it is 'deal X over Y')
Normal sets don't proc if they aren't 5/5, eg backbar syvarra's staff won't proc on the frontbar even if your target stands in your wall of elements.

Also i forgot to mention but there is a bug in the game (which might have been fixed but i'm not sure), where recasting your snapshot dots/hots before they run out after increasing your stats does not increase the tooltip. Like casting poison injection without major brutality, then popping rally/pot, recasting poison injection might not give you the bigger 'deal X dmg over Ys' that you should have. Needs testing though, as Im not sure if it is still a thing.