This is correct, more or less. Each champion will also apply their experience gain modifiers, if any, to the amount that they gain. So a battle worth 8 base experience will give 8*(champion x's experience modifier)/(# of champions present) to champion x, with this calculation performed for each champion on the field. Another way of looking at it is that the champions will each be given 8/(# of champions present), and they will each gain a bonus based on their individual experience modifiers, which do not affect anyone else in the army unless otherwise noted (e.g. the Trainer traits). Thus, for a battle worth 8 experience, you could have a mage gain 5.6 experience (Knowledge + Potential) and a Warrior gain 4 experience, for a total of 9.6 actual experience earned off of the base 8 experience for the battle. Trained units gain half of the base value given to champions, so in this case the trained units would gain only two experience apiece for the battle, unless they were designed with the Potential trait or your champions have army experience abilities (General, Trainer).

A note about the army experience modifiers - these can be viewed as modifying the base experience value of the battle, before division. So if you have a General (+25% army experience gain) leading your army,the game treats it as though everyone in the army - champions and trained units both - hass an additional +0.25 to their experience multiplier. Also, all experience modifiers are additive, not multiplicative, so Champion Potential + General + Knowledge works out to a multiplier of 1.65 (1 + 0.15 + 0.25 + 0.25), or +65% experience, for the champion, and 1.25, or +25%, for the trained troops.

This is incorrect. If the champions of the army get 4 experience each, the trained troops only gain 2 experience each, before modifiers come into play.

Henchmen get whatever amount of experience a champion would get, but do not count towards the number of champions in the army. Therefore, if you have an army of two champions, two henchmen, and a few trained units, and the battle was 'worth' 10 experience, each champion and henchman gets 5 experience (multiplied by individual modifiers), and each trained unit gets 2.5 experience (multiplied by individual modifiers).

This is incorrect. The trained troops get the same as any heroes. If the total was 8, and the heroes got 4 each, then every troop gets 4.

When I get home I'll take some screenshots to settle this once and for all of a battle with two troops and one or two heroes if someone doesn't beat me to it first.

FYI, there are also modifiers to the total exp in regards to army strength. So with one hero you MAY get a higher total exp before anyone gets any exp. Or maybe not, one hero may not be enough to make that difference.

Ack, you are totally right, I brain-farted this one, not sure where the hell I got that from. Here is an old post of mine where I explained it a bit more thoroughly.

https://forums.elementalgame.com/438100/get;3293180

The game has some idea of what the strengths of your army and the monster army are. The difference between these numbers somehow comes into play as a modifier to the experience value of the fight. This is done because there really is a big difference in the challenge for killing an army of trolls with a single level one champion as opposed to killing the same army when you've got a high-level champion with an army of knights in shining armor backing him/her up, and the experience gain is nominally reflective of the degree of difficulty of the battle.

However, we don't know exactly what the modifiers are, nor exactly how they work. We can generally say that more powerful armies earn less experience than less powerful armies do, and that this strength metric is somehow affected by each of the unit attributes (attack, defense, initiative, health, accuracy, dodge, level) and probably also by the traits of a champion or unit (Water Magic IV probably adds more to the 'power' rating than Water Magic II, and special abilities like Reap or Charge probably add some set amount of 'power' to the strength rating). We cannot say, unless someone has done an extensive amount of testing or unless someone from Stardock tells us, how exactly this works out to the experience earned for a battle. So I can't give you a formula that says something like "battle experience is equal to (some sums for the enemy army) times (some multiplier based off of your army)" or anything like that.

The game essentially uses a challenge rating system to determine how much experience a battle is worth and then starts dividing stuff up from there. You can even see parts of the challenge rating system whenever you select an army or hover over an enemy - it's the Weak/Medium/Strong/Deadly/Epic rating - but it's not something that is that helpful for figuring out the system because of just how vague the categories are. You could probably figure out how much each part of a unit contributes to the challenge rating if you really wanted to (by coming up with minimum Attack/Defense/Health/etc values for Medium/Strong/Deadly/Epic armies and playing around with trait combinations to assign values to those), but it's probably not worthwhile. You can probably ensure that you get more or less as much experience as you'd ever get just by ensuring that you try to fight armies with similar challenge ratings (e.g. fight Medium+ enemies if your own army is Medium) and try to avoid grouping champions. Be advised that I have seen games which awarded experience on challenge rating systems where you were penalized for fighting above your own 'challenge level', though I could not say if that is the case in E:FE:LH or not.