In regards to nandroid / radio the only time it will revert back to the orignal radio would be when you have first taken a backup of the phone (before installing a custom rom) and then you install a custom ROM and newer version of the radio... and then if something goes wrong you restore your phone...(as you are using a backup which had the phones original stuff).. Otherwise most people will have nandroid backups that have the newest radio because they are using there new backup which they take after installing the custom ROM. I have written a very long winded post about this here.. does it make sense? Are there any ways to make it clearer. It is difficult to word as it depends on the persons ituation. I.e. which backup they have as there latest... But again a valid point and one which I need to stick in somewhere. Also.. I have added a note about your 2nd point.