these are very specific questions and I'm not sure how to calculate these values.

The best way to get closer is to extract the data manually from the RRD file, import it into a spreadsheet and try to build the appropriate formulae. As soon as we have them, we can discuss how to implement them.

To extract the data, you need rrdtool installed on your machine. If it is not present, issue

sudo apt install rrdtool

For extracting the data from the RRD file, use rrdtool fetch. For example, with
rrdtool fetch weather.rrd AVERAGE -s -100d -r 1h
you extract the 1h averages of all parameters of the last 100 days.

If you need additional help, send me a PN here so that we could continue to discuss by email.