1
You need to provide "Template" and specify the match group number, something like $1$ should do the trick for you.
More information: Using RegEx (Regular Expression Extractor) with JMeter
1
Your solution with powershell makes sense.
Another idea is to use JMeter Maven Plugin which automatically runs all the scripts it finds under src/test/jmeter folder relative to pom.xml file.
You can also pass parameters via Maven pom.xml file.
More information: How to Use the JMeter Maven Plugin
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