My preferred method of communication is usually to start with a phone call before moving on to regular emailing over the course of a project. I believe that it's better to talk more throughout a project rather than less in order to make sure that both designer and client are on the same page. I'm not shy about asking questions to gain clarification on any project, and welcome honest feedback so that we can reach a common goal.
Payment can be made after the completion of a project, on a weekly basis, or upon reaching particular milestones. Which method will work best can be determined at the outset of a project before any work begins.