peasants become mercs. you get them frequently as captives from looters. Bonus: Peasant do not cost upkeep as long as you dont promote them. Nice forgot about that, I usually ignore peasants because I thought they would be useless. There's a mod on the nexus that expands the mercenary troop trees, too.

Your younger family members have events as they grow up to decide skills and equipment. Towns can rebel, which creates a new clan, that also can join other kingdoms if they lose their town. You can turn your companions into lords, which creates a new clan with 2 new lords. The main quest is a curse you can put on a faction to create large scale
Bannerlord is developed and marketed as a sandbox game. Despite the main quest in the campaign mode, you totally can ignore vassalge and kingship and just be a merc or a trader or a smith or a bandit or a questing traveller forever. You can even conquer a castle while being below clan tier 4 becoming a robber knight instead of a king.
For example, say you want your companions to level bow. Find some forest bandits and make a shield wall. Place your companions slightly behind and offset. Then the shield wall will soak up the bandits' arrows while your companions gain XP. Desert bandit hideouts work best for this.
1 - If you become a mercenary, then your employer's enemies will be your enemies. 2 - Not until you become a vassal and get your fief from where you can send caravans. 3 - The fief is already offered to a vassal, not a mercenary - this is an increase in status and the opportunity to participate in decision-making. 4 - Almost everything. . 256 462 296 5 147 377 345 425

bannerlord how to become a mercenary