Question: Will the latest and greatest OS upgrade for the phone fix the ringing problem?
Answer: It should fix the issue and should be found under your profiles.
Question: Will there be an issue with the phone being upgraded with out upgrading the BES?
Answer: You will still be able to activate the phone on your BES but obviously there are a lot of features that will not work that take advantage of the the newer phones and the newest BES. You could mention them about the free version of BESx that would let you take advantage of these features.
Question: If I do a thorough backup and all else fails can I restore back to 4.7?