I see by looking through the questions here at HubPages that you have many questions about religious themes. I hope you are finding answers and not merely posing questions. Some folks with lots of questions seem to be without traction in getting understanding.
The apostle Paul was not a pastor. He was an evangelist...a missionary. Both of these offices carry the idea of a temporary assignment...being sent for a particular and special purpose which is fulfilled and then the individual moves on.
The pastorate is a different office entirely. This person is to remain in place; continuing in the community many times until the end of their lives.
Looking at the words for these offices, we find that "apostle" and "missionary" are both "sent ones" ( the definition of apostle itself).
Apostles were sent by Jesus Christ in person. Missionaries are sent by the church. Both are "sent ones" for the purpose of spreading the gospel and planting churches.
Evangelists are not typically called by the church. It's most often a matter of an individual discovering their spiritual gift and following the lead of the Holy Spirit (as opposed to being sent out by the church).
Paul describes himself as a using a special case (or the Corinthians were an especially troublesome church, lol.) He supported himself (he says) so there would be no excuse by the carnally minded (spiritually immature) Corinthians to doubt the sincerity of his love for them.
When we see the reason for Paul's actions we realize it is not a rule he is creating but rather an exception he is using. Few churches today would treat their church leaders so poorly as the Corinthians did to Paul.
Paul went the extra mile with a bunch of immature and very self-centered believers living in Corinth. Because we love our Pastor we support him and free him and his time for spiritual work. The working Pastor has little time for ministry compared to the one who is supported by his flock. "The workman is worthy of his hire" is the passage Paul uses to explain this important point.