Yes, pottery has been used for thousands of years. Pottery containers are relatively easy and cheap to produce, and humans have always needed to contain food staples, either for transport, storage, or to eat or drink from.
YES
the middle ages
There were many types of 'coat of arms' for a long long time, but the custom was fully developed by the middle ages. It is argued that the different designs on ancient pottery was the official first documented coat of arms. found here: http://www.historicalnames.com/origins.htm
The predominant staircase design in the Middle Ages was the spiral design for stairs. Spiral stairs were used from the medieval ages and are still used in many modern houses.
The hammer and sickle were used in the middle ages for a variety of different tasks. Both items were used to pound things into the ground and to cut grain.
Castles in the Middle Ages were used to keep out enemies.
See the question: What are some weapons used in the middle ages?
In the Middle Ages
people in the middle ages used letters or talking to face to face
because they used wood smoke as a deorderant in the middle ages
knights
to entertain
YES
Yes, polyphony was used during the Middle Ages. We do not have any real idea of when polyphony was introduced, but the earliest texts describing it date to the Early Middle Ages. By the end of the Middle Ages, it was highly developed. There is a link below to an article on polyphony, beginning at the section on its origins.
It was used in the middle ages by monks!
the middle ages
There were many types of 'coat of arms' for a long long time, but the custom was fully developed by the middle ages. It is argued that the different designs on ancient pottery was the official first documented coat of arms. found here: http://www.historicalnames.com/origins.htm