It's up to you how often you want to keep in touch with your developers, as a rule you should expect to get regular updates and make your expectations clear to your development team.

You should have a project manager or dedicated person who will be your primary contact on the development end. Run through the schedule and talk about upcoming tasks each week. Using tools such as Basecamp are great ways to setup project milestones, communicate and share files.

You may also want to setup a Dropbox account if you don't have one already and share files with your developer this way.