Controversies Synoptic Gospels

the synoptic problem hinges on several interrelated points of controversy:

priority: gospel written first? (clearly, 1 text draws another, source must have been composed first.)
successive dependence: did each of synoptic gospels draw each of predecessors? (if not, frequent agreements between 2 independent gospels against third must originate elsewhere.)
lost written sources: did of gospels draw earlier document has not been preserved (e.g., hypothetical q , or earlier edition of gospel)?
oral sources: extent did each evangelist draw personal knowledge, eyewitness accounts, liturgy, or other oral traditions produce original written account?
translation: jesus , others quoted in gospels spoke in aramaic, gospels each written in greek. performed translation, , @ point?
redaction: how , why did put gospels in final form expand, abridge, alter, or rearrange sources?

furthermore, theories try explain relation of synoptic gospels john; non-canonical gospels such thomas, peter, , egerton; didache; , lost documents such hebrew logia mentioned papias, jewish–christian gospels, , gospel of marcion.