After the מחלוקת with קרח ended, we are taught about some of the twenty-four special gifts that were given to the Kohein.
There were ten gifts given to the Kohein on the premises of the Beit Hamikdash.These were limited to items related to sacrifices or Temple services. They were given parts of sacrifices offered on the altar. They were also given the לחם הפנים, the showbread, that needed to be eaten on Temple grounds.
There were four gifts given in Jerusalem. Included here were the ביכורים, the first fruits, as well as the בכור, the first born male animal.
There were five gifts in ארץ ישראל, such as תרומה. And there were five gifts given anywhere. Among these last gifts, were the coins of פדיון הבן.
The Kohein only served two days a year. His group from his geographical location known as משמרות, served only two weeks a year. The Kohein served one day during each of the two weeks.
Therefore, his primary role was educator of the people. He needed these gifts to help with his sustenance.