You will need a flash that fits the Sony Multi-interface shoe. Sony flashes that fit have an "M" suffix. The only other compatible flash I know of is the Nissin i40. Otherwise you will need a mult-interface to Minolta adapter. These should be available on Amazon or B and H.

I do know that Sony doesn't yet have full support for 10.10. Their raw converter and some Play Memories apps only work up to Mavericks..

I'm new but have been following discussions for a while. I have been struggling to become a good amateur photographer for years... Hope I succeed someday.