Considering buying the new Samsung Tab S6 256GB Wifi, however I have a couple of questions before doing so:
I can't answer #1-4, since I know very little about HDR or color spaces.
But as for #5, I have not had any app compatibility problems yet on my S6. All of the Samsung apps and most of the Google apps seem to have tablet-optimized layouts, and I haven't noticed a problem with any other app as of yet. One thing I noticed right away is that the S6 is not nearly as big as I thought it would be. Feels more like an 8-inch tablet than a 10-inch. So even if an app isn't optimized for tablet at all, it still looks fine on the Tab S6 in portrait mode.
This is bullsht. (I made a mistake so that forums will not * the word.) Chrome does not support color management in Android 8.1 and later as of now. You can say to them what you are thinking about them :
But gallery (samsung does support it): https://bugs.chromium.org/p/chromium/issues/detail?id=957376
Which ones support HDR10+?
Nobody and nothing. There are no apps yet. At all. Patches to ffmpeg on HDR10+ (the key library to support HDR) is yet to be applied. Though they are already on patchwork.ffmpeg.com
Is the HD10+ 10 bit (guess so, but rather checking)?
"+" in HDR10+ is about new HDMI and DP dynamic HDR metadata. It has nothing to do with bits. Though of course it is 10 or 12 or 16 bits as any HDR. It is mandatery. And BT2020 gamut (color space and white point). Tell me if you want to know more.
all major apps are optimized for tablets.
Yes, I never had any problems with my apps on tab s4. And it has absoulutely the same display (it does not support HDR10+ and has 90 degree corners though).
Will I be able to connect my new camers (supporting USB-C) and sync photos straight
Yes. It is Android not iOS. You can root you device you know.