Non-dev here. Could i use something like this to customise an existing kinetic typography AE template and churn out new videos? Also do you know any freelancers that would take on such work?
You can customize pretty much any After Effect layer properties, including font, text, colors, etc. So if I understood your question correctly, yeah you can. Regarding freelancers, any Javascript developer should do just fine.
If you can use Nuke you can make a composit script that can take command line arguments, which makes it very easy to automate.