How are the song data created with the BR-1600CD, BR-1200CD, and BR-1180CD compatible for song conversion?

What are additional functions and enhansments of the BR-1600CD Version 2 when compared with the BR-1600CD?

The last time I powered off my BR-series unit, I had the phantom power switched on. However, when I power the unit back on, the phantom power is now switched off. Why is this?

On my BR-series unit, I've created two songs: Song No 1 and Song No 2. I erase Song No 1. Next, I create a new song, and it's automatically numbered as Song No 3. Since Song No 1 has been erased, why isn't the new song named Song No 1?