IOS – MDM that can control wifi and bluetooth

Bingo! you've already got it there in your question.

Your last item "Web clips Credentials and keys" should actually be two - "Web Clips" and "Credentials and Keys" in which case, "Web Clips" is the one you're looking for. A "Web Clip" is a home screen bookmark for a website.

From the Enterprise Deployment Guidelines:

Web Clip Settings

Use this payload to add web clips to the Home screen of the user’s device. Web clips provide fast access to favorite web pages. Make sure the URL you enter includes the prefix http:// or https://—this is required for the web clip to function correctly. For example, to add the online version of the iPhone User Guide to the Home screen, specify the web clip URL: http://help.apple.com/iphone/ To add a custom icon, select a graphic file in gif, jpeg, or png format, 59 x 60 pixels in size. The image is automatically scaled and cropped to fit, and converted to png format if necessary.

You can only have 1 MDM profile installed at a time, so it will not allow you to re-enroll the devices if they are already enrolled (even if the original server is now defunct)

I cannot recall if you can remove the MDM profile from a supervised device, but I believe that you can.

The easiest way would be to probably send a link that can be opened in safari to re-enroll the devices as you mentioned above. You can always take the profile and host it at a different URI so no user account is needed, therefore you wouldn't need to worry about access at all.

Hope this helps a little.

Mike