I've lived on Ramrod Key (Breezeswept Beach Estates) for over 24 years so I know the area well. My kids go to Sugarloaf Elementary/Middle at mile marker 17 and it's K-8. They will go to Key West High School for 9th grade. It's my understanding that if the child resides on Big Pine Key they can choose either Marathon High or Key West High on Ramrod and south it's Key West. And yes there is school bus service from all islands.
I have numerous listings and am very active in both selling and working with buyers on Ramrod Key. If it would be helpful to you I could send you the currently "active" listings for Ramrod. I also know of some homes here that are not yet on the market but soon will be. As a potential buyer you should know that the tide is turning and the canal homes on Ramrod and other islands priced under $400K are selling fast and closer to list price. Now is the time to get going or you will be behind the curve.
If you would find some assistance beneficial in your search I'd be happy to assist and can be reached at my Big Pine Key Coldwell Banker Schmitt RE office 7 days per week at 305-942-6210. Otherwise have an excellent day and I'll see you on Ramrod!