Hey @DiscourseUser,
For sidebars take a look at the Custom Layouts Plugin which creates a framework for adding widgets to sidebars. Then you can any of the available widgets into either the left and/or the right sidebars to make it look more reddit-like.
For the topic list, check out either Topic List Thumbnails or Topic List Previews
For the ability to add upvotes in a question/answer style format see: Question Answer Plugin or Discourse Feature Voting