I can offer clarification on at least one point;
While the type of conflicts a team can engage in is determined by the highest Might on the team, the individual team members still keep their individual Might scores and all that entails during a conflict, barring special exceptions, such as Riders increasing their Might to the level of their Mounts.
For example, if a group of Adventurers (Might 3) ambushed a band of monsters made up of a group of goblins (Might 2), a Dire Wolf (Might 3), and an Ogre (Might 5), the Ogre’s Might would prevent the Adventures from engaging in a Kill Conflict, due to it being +2 Might above them in the Order of Might. If the Adventurers choose to engage in a Drive Off conflict, they would still be considered +1 Might compared to the Might 2 Goblins, and therefore get +1s for actions against them. The Adventurers would be evenly matched with the Might 3 Dire Wolf, and the Might 5 Ogre would get +2s for actions against the Adventurers.
If one of the Goblins mounted the Dire Wolf, then that individual Goblin would also be treated as Might 3, and the Adventurers would no longer be considered higher Might, and they would lose their +1s for actions against that specific Goblin.
If, on the other hand, one of the Adventurers had an ability or item that boosted their Might to 4, but didn’t boost the party’s Might (such as a class ability, like the Elf Ranger’s level 10 Sons and Daughters of Arda ability, or a magic item like the Girdle of Troll Might), then the whole party would be able to engage in a Kill conflict with the above group of Monsters, because the type of conflicts that are possible are determined by the highest Might on the team, but only the Adventurer with the ability or item would be treated as Might 4 during the conflict. Only they would get +2s for actions against the Goblins, +1s for actions against the Dire Wolf and it’s potential Goblin rider, and the Ogre would only add +1s for actions against the Might 4 Adventurer. The other Adventurers’ bonuses and penalties would be unaffected.
Hope this helps clarify at least one of the advantages of mounted combat.