[Sombre]

1) I don't really understand your question. If a unit is specified in the #hero1 field then he may appear as a hero. If a unit is specified in #startcom or #startscout then he will appear as a starting commander. Heroes have no intrinsic properties, they do not have the unique tag in basegame, it's just that each hero event may only happen once.

2) Yes, you can start with 2 commanders (all nations do in fact). These are defined by #startcom and #startscout.

3) Neither heroes not multiheroes are instrinsically unique. It's actually the #multihero1, #multiehero2, #hero1 to #hero5 events that are unique - they can point to whatever kind of monster you want and it will turn up as a commander. So they could all point to a militia unit and if you got all 5 hero events you'd get 5 militia commanders out of it. If you want to add a unque tag to a unit (only one of this unit may ever be in the world at a time) you need to copystats a unique unit. This brings some more problems, but if you want to know how best to set it up I can tell you.

4) There is a base 3% chance of a hero event, I believe. Luck adds +1% per point. Misfortune is -1% per point. So with misfortune 3 you get no hero events. It decides which hero appears from the event at random, but #hero1 to #hero5 cannot happen more than once. #multihero1 and #multihero2 can happen an infinite number of times.

Lastly, that ability is tied to the nation ID number. So if you want your nation to do that, you'll have to overwrite Arco.