1. Only the main hero (Gem) progresses to the next mission.
2. In addition to this hero, you can leave one more hero in the final save if that hero is needed to perform the winning action (attacking the last hero/castle of the opponent).
3. If you have Gem and another hero in the save, the sum of their stats will be calculated based on the hero with the higher stats.
Added 6 minutes later
and the rest can be recruited in the tavern, by the way, already at a higher level, like on the first map.
Все люди - братья, но в каждом из нас спит волк.