None of your existing notes will be lost if you drop to Free. But if you already have more than 50 or more than one notebook you will not be able create any more. You can edit, export, delete and merge existing notes within the general Free limitations. So effectively dropping to Free will change your account into an archive. You could open a second Free account and use that up to the 50 note limit. I think you could also share notes from your existing, now Free, account without affecting your 50 note limit. You'll have to try that and see.
As for the price rise, I doubt that there is any reason to think that a price rise next year will be of the order that has been experienced this year following the takeover. My view is that this is a reset of the prices to take account of around seven years without any increases. Next year probably in line with inflation.