Questions about Mvp++ (and other ranks)

[potatopuggg]

1. Is Mvp++ not available for a lifetime?
2. If I bought a rank before my Mvp++ do I go back to the rank I had before or does my rank get wiped?
3. Can ranks be stacked (example: I buy 2 365 day Mvp++ ranks do they stack?)
Thank you for your time.