Regarding hosting – We indeed host the content on our servers. However, we actually view it as a benefit for our users. The information is kept secure in AWS servers and we deal for you with all load and optimization issues for images/videos/etc. As an example, we will serve small images on mobile, and larger ones on a desktop to optimize performance. Can you elaborate on your concerns with this issue?
Regarding SEO – using quizzes and polls is actually a great way to improve your SEO since they cause users to spend a lot of time on your pages, something Google really values these days. While we can’t commit to how Google scans/indexes content, we don’t see a reason why Google won’t regard polls/quizzes you create as the content of your site.