Can you explain combat in more detail? How does movement work, and does the terrain have any effect on it? How do barricades work? Does combat primarily consist of attacking and moving, or do you use special actions on each turn?
In combat, there are two things each character can do every turn: they can perform an action, and they can move a certain amount of spaces. The action can be an attack, it can be the use of an ability, or it can be converted into another move. Your movement and your action can be performed in any order, so you can move forward, shoot, and move back if you want (which is in fact a trick the AI uses a lot). Because you get to move all your people before you end your turn, it's fairly straight-forward to set up advanced maneuvres such as flanking or combination-attacks. The terrain has no effect on movement.
In addition to what your followers can do, you also get to bring up to 3 of your inventory items into a battle with you. Just like with character abilities, every one of the items you get are active rather than passive. Two examples of such items are barricades and traps, which you typically get to place before the battle begins. Of course this is only allowed if it makes sense in the context of the event that triggered the battle - if you're attacked in an ambush while travelling, the AI gets to take its turn first, and you will not be able to put down traps or barricades. There will be other items that aren't restricted to the first turn, however.