Skyrim SE - No Follower/Non-essential dialogue overlap

[mantyke2]

This would immensely improve the immersion of the game. I'm a total noob when it comes to making mod making, but I'm thinking of making a mod like this depending on how the dialogue scripts in the game work. I assume a simple script that either checks when an NPC wants to start speaking or when a player crossed through a dialogue trigger box would be enough, but I'm not sure how hairy NPC dialogue can get.

Features:
NPC to PC dialogue now employs a queuing system, the NPC with the dialogue first in line gets to speak first
If quest dialogue is currently happening, for example Jarl Balgruuf the Greater to Proventus Avenicci during early quests, no NPC to PC dialogue can enter the queue

This allows the following:
NPC to NPC dialogue does not respect the queue, for example a shop owner talking to their child
Bards may still sing and play music without respecting the queue
NPCs talking to no one/to themselves do not respect the queue, for example Heimskr in Whiterun

In order for me to make this mod I need to know several things:
Is there a flag that specifies whether dialogue is NPC to NPC or NPC to PC? Maybe a variable that specifies the target of the dialogue is the player?... How does the game differentiate dialogue targets?
Is there an array of NPCs that have things to say with matching dialogue IDs in some sort of trigger box? Maybe the NPCs check where the player is everyone once in a while? Maybe there already is a queue system?... How does NPC dialogue work?

Thanks