Answer to Question 1
Beats/pulses are apparent (metered) and (B) grouped into a triple meter, a meter with a number of beats divisible by 3 (1 2 3, 1 2 3, etc.).
With each phrase being 4 bars long, illustrating the most common European musical phrase length
4. Why do Oifn Pripetshik, Joy to the World and A Mighty Fortress sound like European compositions?
All three songs are based on the common European major/minor scales and related harmonies.
All three songs are in a common duple/triple meter, grouped into four-bar phrases.
Answer to Question 2
Metered music has an obvious beat or pulse organized in a repeating pattern.
Unmetered music lacks an even pulse or repeating pattern of beats.
An ostinato is a musical line that repeats throughout the piece.