Yes, a vocation is a call from God to serve Him in a special way as a priest or religious. All people are called to serve Him, but priests and religious are the spiritual leaders of their communities. There is no time limit to how long or how brief a period should be spent in discerning a vocation. The key to hearing the call is being open to the signs communicates to us.
Marriage is a separate calling from the priesthood or religious life.
One does not jump to either marriage or a religious vocation because he or she is dissatisfied with their present calling. The responsibilities of each are very different. Brotherhood has its own requirements. Each religious order has guidelines for the training and discernment required to take vows as a brother. Keep in mid that the brotherhood is not a second choice for those who cannot be priests.