The binary format described in the support article you linked pertains to binary files exported via exporting raw data (which is different from the .sal capture file generated when saving your capture). This is mentioned at the top of the support article.
We don’t publish official documentation, nor maintain documenation, for the .sal file format, but we provided some unofficial notes about it in the forum post below.
As for adding HLA support for your custom analyzer, we’ve provided some guidelines below.
For the other questions I haven’t addressed, I’ll meet with the rest of the team here and I’ll follow up with you on those topics.