Hi,
– For the keyword highlighting yes, I recommend using the media service addon. You can get by with the free license most likely – if your files are generally 10MB or less.
– For the paywall you probably have a plugin or a custom code of some sort, WordPress does not have a feature in core for that. Every single one works differently, so it’s hard to tell.
– The results page is a theme feature. I usually recommend using a page builder if the current theme does not have customization options for it. Most newer themes do have an option to customize the results archive loop, try looking if there is anything in the settings.
Unfortunately I am not available for custom jobs – support/development as well as videos, documentation etc.. takes away all my time 🙂