Adjustments in an XML export

Hello,
we chose your plugin to realize a very difficult project consisting of several communication steps.
The plugin is really very clear for us as complete beginners and the explanations helped us a lot with one point or another.
Since we have to meet the specifications for our project down to the last detail, the following questions have arisen. Maybe we can find a solution together?
The first problem we have is in the <message header>, the default requires an indication of when the file was created for the values ??generation_time and generation_date. Here too we have to pay attention to the output value hh:mm:ss and dd.mm.yyyy. This is what the default looks like

How can we output these values ??there?

After the <message_header> comes <Sortimentstruktur> and then <products>. Both contents are in a loop. See template

So we tried to assign <!– BEGIN LOOP –> and <!– END LOOP –> to both areas. Unfortunately this only seems to work once with the loop statement. How can such a task be solved?

I also wanted to ask whether there is a way to get the respective IDs and names of product categories, not only at the existing level, but also at the parent level?

Kind regards,
Johannes