1. He is using a Rift and boxed FSX, no Steam or SteamVR involved.
1.5. I recently began having d3d11 errors at launch and we determined that it was the SteamVR update. Reverting to stable SteamVR does fix the d3d11 error at launch, in case anyone does have that issue.
2. I recently began having the same kinds of issues as OP. Starting in an outside view, out of memory errors (on a 32GB machine) and more annoyingly... crashes when i try to open instrument or external views.
I'll open a separate thread for my error, in case my issue is different. Just (hopefully) adding some context.