the emperors affected japan by giving the citizens of early japan courage and by splitting each land to the daiymo so there wouldnt be any conflicts and that effected japan by making it so that era of japan lived for a longer time then it would have been.
It is impossible to follow the old ways of the samurai. Samurai means to serve. You would serve the emperor or the shogun or daiymo, depending when in time you were living. Samurai followed bushido, or way of the warrior, devoting to life and death everything to follow a good path through service. The closet to this in a modern day way would be a Buddhist, serving in the army during the a time of war. Samurai were a class of person in Japan, when the samurai class was disbanded, so was its way of life.
A hiarchial system. There was the Emperor who was in charge, The shogun (who had the majority of the real power in china) and then there is The samurai who were very respected warriors of their time, Then there are the farmers (who produced the food in china, obviously.) Then there were those who made the usefull things and equipment for the people of china, Then there were the merchants, Then there were the daiymo who were considered as "non humans" I hope this helped you out.
Japan's geography helped in various ways. the mountains in some regions meant that passes into that territory were easily dependable against larger armies. furthermore winter weather usually meant an end to the campaigns of the Daiymo for the year due to the difficulty in moving an army during the winter rainy season. furthermore, movement by ship during hurricane season was not feasible leading to a focus of movement by land. Mountains also meant that outposts and castles in the mountains were difficult to attack and hard to bypass, because doing so would mean an attack to the rear of the invading army.