If the archers are causing you problems, try attacking them first. They will switch to a melee weapon up close.
You can set hotkeys to use potions (health, mana, restoration or stamina), though only the lead character will drink. You would have to switch to the other character (via hotkey or otherwise) and hit the hotkey again to have both characters use a potion. Use of the space bar to pause the game helps with this.
To assign a hotkey, open the potion bar by clicking on that icon beside either character's portrait, hover the mouse cursor over a potion icon and press one of the function keys.
The first summoning doll is not until after this level.
