The enrollment could take some time. I had many problems to sign up. I hope they fixed it now. Also I had to wait a few days after I was finally able to do the payment.
If you choose update while holding alt/option (Mac) or shift on (Windows) instead of clicking on restore in iTunes, normally nothing should get lost. But as already mentioned, a backup should be made, just in case anything goes wrong (never happened to me).
And the problem with not getting OTA updates, when you are not already on a Beta or a too old one, is now solved with the new profile what you can download there.