Should Muslims know all of the Companions? It is not a requirement for Muslims to know any of the Companions. However, we should learn about the life of Prophet Muhammad (PBUH).
When we start to learn about Prophet Muhammad (PBUH) we are going to learn about his family and his Companions. We will definitely learn about the four rightly guided Caliphs after him.
Should we follow the Companions? Scholars look to the Companions as examples for us to follow. They look to the verdicts of Islamic law given by Abu Bakr, Umar, Uthman and Ali.
We should look back to their lives as good moral lives and we should try to emulate their lives and examples.