Let's see if I can play Devil's advocate here...
Your goal is to disprove that you need to have (some) knowledge, that you must associate with the congregation, and that you must preach, all before getting baptized, right?
Now, in the case of the 3,000 baptized, the Ethopian, and Lydia, they were either Jews or proselyte Jews. Therefore a dub could argue in their case that they had already had a basic knowledge of scripture, and that they associated with the Jews. But the need for this becomes undone by the cases of the jailer and the centurion. The dub in this case will probably argue that the congregation was young, and therefore there was a flexibility with the rules. I don't know how they would support this scripturally.
The cases of the jailer and the centurion destroy any uniform pattern of taking in knowledge (based on their faulty translation of John 17:3), association with the Christian congregation, and preaching before baptism. There is no proof that either person did these things.
I was reading a bit about qualifications...specifically, whom was qualified to teach. The overall theme was that the Holy Spirit would make itself manifest in those who were qualified to teach. The only scripture I can see to support having knowledge in order to be qualified to teach (unbaptised publisher) would be 2 Timothy 2:2, wherein Paul says that if Timothy related to faithful men what Timothy heard from him, these faithful men in turn would be qualified to teach. These faithful men were already baptised, but the person might use this scripture anyway.
However, all of 1 Corinthians 2 basically destoys any claim that you need to be examined before baptism.
The baptism is the gateway, not the goal. You get baptised, then you preach. Paul was writing to baptised persons when he exhorted them to get rid of their unclean practices (1 Corinthians 6:9,10, Galatians 5:19-21). But dubs will apply these words to unbaptised people anyway.
I'll look into the Organization book to see what support they give for the Questions for Baptismal Candidates.