1. Yes, I think you're right. The workflow looked sub-optimal as I was only sharing my browser window, so you didn't see the file-picker show up. And yes, I need to discuss mobile options with Outlandish.
2. I think we've got a couple of options for the first page a user sees. If they choose tags on sign-up, then we can show related communities and collections. If they don't, however, we'll need a generic page, which can be featured communities. Remember, as well, that notifications will guide users to relevant content, too!