You can add it to a reviewt template or a badge. For a review template look under the More Settings tab when editing a review template.

This should already be limited to jpg and png. Have you tested an svg file?

Try temporarily de-activing the cache plugin to see if that is indeed the issue.

https://search.google.com/test/rich-results

Might take some custom coding to pull the reviews from the database. You could turn on the schema for the review template. Google should be smart enough to read both schemas on the page.

Can you check them now?

I just filed a support ticket with the scraping service. They are looking in to it. I suspect that VRBO changed something on their end.

Check it now. That "still working... number 1 in queue" means that you are the next in line.

The VRBO Crawl method is currently down, however you can still get the reviews using the Review Funnel method. I'm working the Crawl method, but VRBO is getting at blocking web crawlers.