Try the following:
https://petscan.wmflabs.org/?psid=5011942 — for articles
https://petscan.wmflabs.org/?psid=5011963 — for subcategories
Most likely, you've just forgot to increase value of the "Depth" field in GUI.
I wrote Wik2dict a decade ago to turn MW database dumps into the dict format. It's python code. Could help you figuring out some things.
The best way to convert this xml into mysql is by using mediawiki's xml import functionality.
If you don't have a good reason to import the dump into mysql it's better to avoid it as it's extremely slow with such a large ...
I found some hints for the schema here https://meta.wikimedia.org/wiki/Help:Export#Export_format
To read manually the XML, try using a viewer like:
head -n [numberoflines] dump.xml (gnu/linux terminal)