I'm planning to build a small traditional wood fire oven, and I'm wondering how is the correct usage of the fuel (I'm planning to use regular firewood): Do I have to wait, until all the wood burned down to charcoal or can I close the oven front door with some logs still burning? I don't want smoke to interfere with my cooking. I'm mainly thinking of cooking stews or making roasts, so cooking time will be about several hours, so do I have to wait until the logs are transformed into charcoal? The oven will be located outside on a terrace and looks similar to this picture:  
A lot of the "cooking" with an oven like that is intended to make use of residual heat stored in the brick, etc. The process of burning the wood down to coals heats up the brick oven itself which provides a easier, more consistent radiant heat. You're not really looking to do "campfire" or "fireplace" cooking here. Letting the logs burn down will also help reduce smoke, etc. You might need several hours to get the oven up to temperature to do any actual baking. Or, you could cook something like a lunch pizza making use of the smoky fire while the oven is heating up, and then slide in your dinner stew/roast to cook as the oven begins to cool down. Properly constructed the oven should hold heat for many hours. In some circumstances ovens like yours are kept at temperature for days on end and used for multiple baking tasks throughout the day. Here's a breakdown of how to get the most out of residual heat and meal planning for wood https://www.fornobravo.com/brick-oven-cooking/brick-oven-cooking-techniques/retained-heat-cooking/ I imagine you might already be aware of this website (Forno Bravo) but it's a great source of information on wood-fired brick oven cooking, construction, and other resources. It also has a vibrant community of enthusiasts. There are many others available as well. 