1. As you are proposing a date far outside the known human history, onus is on you to prove that it was no moon day. It is reasonable to assume that all Brahmana texts are written in same period. Since other Brahmana texts mention full moon explicitly, the weight of evidence is against you unless you can prove otherwise.

2. It has been discussed in detail in the article.

3. This is common sense. Brahmana texts are not going to be separated by over 7,000 years.

4. “Extraordinary claims require extraordinary evidence” - Carl Sagan. Since your claim is extraordinary, onus is on you to prove that it was not full moon day as other Brahmana texts clearly mention full moon for same observation.