1.1. At the moment it is.
1.2. I will need to understand the relevance of the data. However, post-updating from the archive on the Meest site is more important to update the actual structure of the data base, and also the logic, so the fields in the dodniks change from time to time. First of all, it's important to us that the Meest API has few methods for importing, and not just downloading, a file.
2. There are no tabs for the "/meestexpressinvoice/" process, such a block of the process with detailed data on TTN, like for example, in NP, there is no such thing.
3. In OneBox, you can’t do it at all
You can also refer to the Meest documentation, for example
https://api.meest.com/v3.0/openAPI/print/declaration/713-8439863/pdfInvestigation block abo diyu z rozdrukivki TTN in OneBox - 4 years.