DropBox Pro

I'm thinking of upgrading to DropBox Pro so I can access all my files from everywhere. I've earned all my referrals and have 22.5gb now. I need more space for all my photos.

Have a few questions that hopefully someone can answer.

1. Is the 1tb Pro storage in addition to my current 22.5gb?
2. If I downgrade, back to basic, do I get back the 22.5gb I had prior to upgrading?
3. I see Pro referrals get 1gb. Can I refer 16 more people to get 16gb more?
4. If yes, and I downgrade from Pro, do I get to keep the 38.5gb?
5. I've read if you upgrade to Pro, they retro back your referrals and give you more storage at the time of upgrading. Those articles were with the old Pro plans. Do they still do this if I Upgrade to the new Pro account and give me the extra 16gb for life?

My wife and I will be using just the one pro account for both of us. A tb is overkill but at $99/yr is a good price.