Your saves are currently on the offline client. When mp drops there will be two clients: a server authoritative MP client and an offline SP client. Your saves will stay on the offline SP client so as long as you're OK playing offline you can play your saves, but if you want to play online you'll need to start fresh.
Very close and this was what we had said in the past. We no longer are going to be splitting the clients. Now, it's just one client that you can run in offline mode if you want.
Edit: You'll still only be able to play offline characters offline and online characters online.