Which structured data (e.g., Microformats or Schema.org) should I use for page with FAQ?
There is this: https://schema.org/QAPage
Which you can indeed use …
and validate: https://search.google.com/structured-data/testing-tool
To build your own FAQ page.
<div itemscope itemtype="http://schema.org/Question"> <h1 itemprop="text">What does FAQ stand for?</h1> <div itemprop="acceptedAnswer" itemscope itemtype="http://schema.org/Answer"> <p itemprop="text"> A: Frequently Asked Questions </p> </div> </div>
This is not only for Q&A sites, but also for FAQs, as
Question explicitly mentions (bold emphasis mine):
A specific question - e.g. from a user seeking answers online, or collected in a Frequently Asked Questions (FAQ) document.
There is no schema entry for FAQ, you most likely best of adding it as a 'WebPage'. or using the about. It's not required to use rich snippets for all pages. It holds little SEO weight if any. Google will be able to establish it as a FAQ page without any markup of this type.