Put them where they are most helpful: Product pages (to overcome objections), Blog posts (for SEO), and a dedicated Support/FAQ page (for general trust-building).
Keep them between 2-4 sentences. The goal is a quick, direct answer. If a question needs a 1,000-word explanation, it should be a separate blog post linked from the FAQ.
FAQ schema allows your questions and answers to appear directly in Google search results (rich snippets). This increases your real estate on the results page and improves click-through rates.