The 95% coverage is a non-issue as far as I am concerned. It's getting blown way out of proportion.
In the days of film SLRs, most SLR viewfinders did not show 100%. I think that my Nikon F and perhaps my Nikon F4 might show 100%. The and millions and millions of SLR users without 100% viewing did just fine for many decades.
I haven't seen exact specifications from Nikon. Until then, it remains to be seen if the viewfinder shows 90% or 95%.
The other way of interpreting what 95% could mean is to take 95 percent of the full sensor size area:
.95 x 860.4 sq mm, which is 817.38 sq mm.
If Nikon marketing is being unclear about that, then shame on them! But I'm not worried. It's a non-issue. Rarely do I frame things to tightly that I'm worried about the last pixels around the edge. It's common for me to do a little cropping anyway.
I like the built-in flash. As much as a separate electronic flash unit performs better and offers more options, I found that the flip-up flash is very handy and adequate for many situations.