I'm updating this thread for future reference.
After the 2/17/16 firmware update for the Surface Pro 4 all the issues I listed on the OP minus the issue with Edge sometimes consuming too much CPU time seem to have been resolved.
After the update the device is faster, has better battery life, standby now uses little power and I haven't had any display driver crashes or freezes even when connected to my dock and having an addition monitor to drive.
I'm still very disappointed by how Microsoft dealt with these issues without clear communication and supports response was just about useless. In the future I'd like Microsoft to be a bit more transparent about what they are doing to fix issues on a device that I dropped nearly £2K for.
That said I'm thoroughly happy with my unit now and look forward to it getting better with further Windows and firmware updates.