First rule to become successful in Battle Brothers: Know when to fight and when to run. You’re running business -mercenary company. Act accordingly. When you face enemy you can’t beat, retreat. When facing impossible contract, cancel it. Penalties for canceling contract are usually very light. Knowing to asses level of danger enemy pose to you is part of the experience gained by playing the game.
That said there are few tricks you can do to overcome stronger enemy. You can for example lead enemy in to allied group. When attacking strong outpost, you can try finding roaming enemy group and leading it in to enemy outpost you want to attack. Let two groups fight each other then destroy those who remain. Be careful however, two groups have to be hostile to each other for trick to work, otherwise they will gang on you. Also don’t lead too weak enemy in to fight with much stronger enemy. Strong enemy will defeat weak one without sweat and will gain morale instead. Also don’t use direwolves for this, they are too fast and have too high initiative so in the battle they will reach you before you can back away to let two enemies fight.
Second rule, you have to accept that you can and will loose from time to time. There’s no way to avoid it. Keep spare armors and weapons and try to have few brothers in reserve with some experience (rotate them between battles). Keep financial reserve.
As for your questions:
1. I did not experience such thing. Early game single skull missions usually throw at you either thugs, mix of thugs with few raiders or if enemy is composed of raiders only, they are inferior in size.
Game seems to factor size of your company in to difficulty scaling. Don’t try to over-expand too fast early on, make sure that you can outfit every new recruit with decent gear. At the beginning this means 30+ armor and helm and a shield. Thick tunics, aketons, that sort of stuff.
2. If interrupted during delivery mission, you are being given option to surrender the package. You have to consider if 500 bucks is worth fighting well equipped and trained enemy. In the beginning of the game, probably not.
Generally speaking, single skull missions are safe to take. But there’s always element of randomness involved so be prepared to abort and retreat.
Good contract is one involving good pay and little risk. You can’t know exactly what are you going to face until you face it. Again, don’t hesitate to abort or cancel mission if pay is not worth the risk. If risk involves loosing several brothers, pay is likely not worth it.
3. With greater numbers. If you don’t have numbers, don’t fight them. You should use early encounters with raiders as a source of improved armor. Fight them only if you are at the advantage and try to isolate one with best armor by killing everybody else first, surrounding him and stabbing to death with daggers. Les damaged armor is,
higher the chance to appear in the loot screen. Buy yourself few nets to incapacitate dangerous foes. Have few flails in company with competent brothers. Many raiders don’t carry helmets, bash their heads to kill them without damaging their armor.
As for hedge knights, don’t ever contemplate engaging one at the beginning of the game.
4. Don’t know exactly, but size of your band, level of brothers and their equipment matters most. There might be other factors, like game days passed and your renown.
That said, unless you’re get ambushed, you have always time to retreat from human opponents. They have the same movement speed as you and distance at the beginning of the fight is such, that they can’t reach you in just one turn. So unless you do something stupid, you can retreat to the edge.
However you don’t have to be at the edge in order to retreat. You can hit retreat button at any point of the battle. Brothers not on the edge will just get injured. They won’t get killed even if engaged in combat.
Consider buying falcon and give it to one of the back line guys with high initiative. He will help you reveal enemies at the start of the combat so you can decide if to fight or retreat.
When facing roaming groups of the enemies, pay attention to the icon they have. It always shows the highest level and most dangerous character in group. You can asses enemy strength even in cases when tool tip don’t reveal that information (direvolves, nachzehrers).