dwsync.xml files are created by dreamweaver to keep track of file versions. You can delete the versions on the server (and locally) to prevent these errors. They are not necessary files.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.