Acts 2:43-47
43 And everyone kept feeling a sense of awe; and many wonders and signs were taking place through the apostles. 44 And all those who had believed were together, and had all things in common; 45 and they began selling their property and possessions, and were sharing them with all, as anyone might have need. 46 And day by day continuing with one mind in the temple, and breaking bread from house to house, they were taking their meals together with gladness and sincerity of heart, 47 praising God, and having favor with all the people. And the Lord was adding to their number day by day those who were being saved. NAS
The church before Paul was in one place in Jerusalem and ate their meals in various houses. As to Paul's teachings if you accept Peter's letters then you should also accept Paul's:
2 Peter 3:14-18
14 Therefore, beloved, since you look for these things, be diligent to be found by Him in peace, spotless and blameless, 15 and regard the patience of our Lord to be salvation; just as also our beloved brother Paul, according to the wisdom given him, wrote to you, 16 as also in all his letters, speaking in them of these things, in which are some things hard to understand, which the untaught and unstable distort, as they do also the rest of the Scriptures, to their own destruction. 17 You therefore, beloved, knowing this beforehand, be on your guard lest, being carried away by the error of unprincipled men, you fall from your own steadfastness, 18 but grow in the grace and knowledge of our Lord and Savior Jesus Christ. To Him be the glory, both now and to the day of eternity. Amen. NAS
If you know anything about Judaism or have read the OT then you should understand the priests were supported by the tithes paid by the other tribes. So a paid priesthood is Biblical.
Constantine legalized Christianity in 313, not the 5th century. Although I agree modern day denominations are not Jesus' plan for His church to denigrate God's truth based on the actions of men is short sighted. God will judge those who are religious and reward those who are members of the Body of Christ.