"O holy mother of God, remember us, I say, who make our boast in thee, and who in hymns august celebrate the memory, which will ever live, and never fade away. And do thou also, O honoured and venerable Simeon, thou earliest host of our holy religion, and teacher of the resurrection of the faithful, be our patron and advocate with that Saviour God, whom thou wast deemed worthy to receive into thine arms." - Methodius (AD 230-311),
Oration Concerning Simeon and Anna
More early sources on veneration of the saints
here. If you include veneration of relics as veneration of the saints, there's the
Martyrdom of Polycarp which records veneration of the bones of Polycarp in the 2nd century.
Plenty of examples of confession even as far back as the 1st century. If you're looking for a source that uses the word ἱερεύς or sacerdos exactly, a safe bet is Origen's
Homilies on Leviticus 2:4 from the 3rd century.
Again,
easily disproven. Justin Martyr's
First Apology couldn't be more explicit: "For not as common bread and common drink do we receive these; but in like manner as Jesus Christ our Saviour, having been made flesh by the Word of God, had both flesh and blood for our salvation, so likewise have we been taught that the food which is blessed by the prayer of His word, and from which our blood and flesh by transmutation are nourished, is the flesh and blood of that Jesus who was made flesh."