Valheim multiplayer difficulty scaling

I am looking for a thorough explanation about Valheim difficulty scaling when playing with multiple people inside a same world. The only information I could find with a quick google was this wiki, which states:

Creature health is further increased by 40% for each nearby player after the first at the moment it spawns.
Hostile creature damage is further increased by 4% for each nearby player after the first at the moment it spawns.

Are these the only rules on scaling difficulty? Do these rules also effect any boss spawned? And what is the value for "nearby"?

On the second point, could I spawn a boss with a single person and later come back to wreck his poor guy with 10 people?