Generally if you’re asking for any information you want to have a privacy policy, even if it’s as simple as “We don’t share your information with anyone for any reason”. Just make sure it’s true.
If you’re going to post any information about someone that they’ve provided, you want to have a privacy policy and an “I agree not to sue the hell out of you” agreement page. (this is what lawyers call it, you know, when they’re hanging out with other lawyers)
If you’re just showing you’re own stuff, it isn’t really necessary.