Deleting An Application

Moving it to the Trash is an acceptable way to delete an application from your Mac. However, doing so will leave behind prefs files and possibly some application support data; this is normally ok because after the application is Trashed they don't do anything other than take up a small bit of drive space.

As dialabrain indicated earlier, if the application has an Uninstaller, it's better to use that because the Uninstaller should remove everything associated with the app.

Not usually. Many apps have a built-in uninstaller.