What is the best way to go about reading and writing simple configuration data like we used to use App.config and Web.config available thr
Metro apps don't have exact equivalent of app.config/web.config.
Instead you should use package.appxmanifest to configure windows store specific values.
For local settings you should use ApplicationData api.
If you want to configure application after it is deployed you could simply load remote xml or json file at application start up.