I think there is some confusion here over what was selected. Keep would be to keep your existing ranks. It would not keep the existing system itself. That has changed in the new version and cannot be reverted to the old way of working.
1 - Ranks have gone - I can see its now using the default rank set. I will need to create a ticket and get that escalated for you to see what has happened. If you had few ranks, it may be worth deleting them and simply re-adding. If you had many however, I can escalate if needed. Let me know
2 - Yes, you can delete the badges that are there if you wish.
3 - Yes, this has changed entirely. You would be best to take a look at the following guide for how the new system works. There is actually a lot more you can now do with the system than you could previously, so you may actually find it to your advantage. You could have course delete all the rules and have the "one point one post" rule set, which is essenially what happened previously. There were not points as such before. It was simple number of content