Elemental/Damage questions

[RKNM]

Curious as to which is better. To me, it seems easier and more impactful to get percent damage increase, as you can just level up a weapon for bigger returns.

How does elemental damage increase/scale?
Does it go up with level as well? Is the elemental damage shared/split with the overall damage, or is it a flat independent increase of the elements damage on top of the overall physical damage?
Will adding gems % increase only the elemental damage %, or does it also affect the overall damage %?
And does increased elemental damage increase elemental status buildup, like flame or lightning? (btw, what does lightning damage buildup do? I know frost freezes on buildup, and fire and plague does DOT damage, but not sure what lightning does)

Sorry if confusing questions, but a little confused on how elemental damage is calculated/does.