Experience Rates With 0-5 Other Group Members

[Axoc]

Here on the forums, on the subreddit, on the wiki, and in-game I've been told about a "full group bonus" that means if you have a group of 6 members then you have more experience gain than if you have a group of 4-5 members. I've also been told that all experience negative modifiers (for example Human Ranger -40% , Iksar Necro -32%) apply to that specific character only, EXCEPT for hybrid -40% deficit.

So for example if the group makeup is:
Human Ranger -40%
Human Monk -20%
Halfling Warrior +15.5%
Dwarf Cleric +0%
Iksar Necromancer -32%
Iksar Shadowknight -68%
(not ideal I understand but these combinations exist only to highlight the experience modifiers)

Then everyone in the group would receive the Ranger hybrid deficit, resulting in:
Human Ranger -40%
Human Monk -40%
Halfling Warrior -40%
Dwarf Cleric -40%
Iksar Necromancer -40%
Iksar Shadowknight -68%
(the higher number is taken, correct? Or are they added together or multiplied?)

This means that as long as one of the four hybrid classes:
Bard
Paladin
Ranger
Shadowknight

Isn't in the group, then the experience rates for all members will be their own personal experience modifier, correct? When they group with a hybrid, how is the new modifier calculated?

Also I have seen from personal experience that the ideal number of players (from a minmax perspective, not a fun social perspective) seems to be 3:
Solo has the most experience per kill but the most downtime
Duo has less experience per kill but the lowest downtime while actually still having downtime
Trio has less experience per kill but no downtime
4 people has less experience per kill but such a high amount of downtime you never go OOM unless constantly nuking
5 people has less experience per kill but such a high amount of downtime you never go OOM with even higher mana than 4 people
6 people has less experience per kill but such a high amount of downtime you never go OOM with even higher mana than 5 people

This means that 3 is the ideal for minmax, not 6 as the rumor goes, correct? But 6 is better exp than 4-5, right? If this is entirely wrong, could somebody answer and explain both of these questions for me please?