Hi Francie,
Sorry to hear about your son's heart problems. I should prefice my remarks by saying I do not practice pediatric cardiology and never see patients in this age range.
If this were an adult, yes I would start a medication at this time. It might even be reasonable to add a beta blocker, but beta blockers at this age my have some less than desireable side effects.
The follow up question is more of a judgement call. If you would prefer a 6 months follow-up, it would not be unreasonable and I am sure your doctor would be willing to reevaluate.
Both a repair and a ROSS procedure are reasonable at this age. If your emphasis is for fewer long term surgeries, a mechanical valve would decrease the need for future surgeries, but, as I am sure you are aware, requires coumadin.
I hope this helps and good luck.