In regard to Acts 22:16
Paul was not preaching baptism here....Ananias was the one baptizing Paul, he was devout to the law
Scripture does not state why Paul was baptized, only that he submitted.
Ananias was sent by God. Why would God send some to baptise Paul if it was irrelevant?
Moreover the baptism was to was to wash away (forgive) Paul's sins, Just as Peter said in Acts 2:38