Moving apps to App Store?

You would need to contact the developer. If the standalone versions do not update through the app store, and you want to get the updates though there, rather than through whichever update mechanism they are using, then ask them if you can do this.

There's no realy mechanism in place for this from the App store side. You need to work directly with the developers.

Its possible. But it would have to be done by the developer. Unless the developer moves the App to the store, and pushes updates through there, there's no way for you to unilaterally do this.

The store can't magically access the developer's website to grab updates for the Apps. The developer needs to submit the apps and updates to the store themselves.