Here are the answers to your questions:
1. Invading groups of Germanic peoples overran the Western Roman Empire which was already weakened, and invading Germanic peoples raided Rome and overthrew the last Roman emperor, ending the Western Empire.
2. Feudalism (political system where people had rights and responsibilities to those of higher rank) and Manoralism (economic system where people lived and worked on isolated self-sufficient manors).
3. 1066
4. The Crusades were a series of battles between Christians and Muslims in the Middle East where Christian knights wanted to take the Holy Land and give it back to Christians.
5. Classical Era (500 BC - 600 AD