Wintersun

Keep the cable length to 5 meters or less for a USB 2.0 connection and to 2 meters or less for a USB 3.0 connection. With USB 3.1 the maximum cable length is 1 meter.

They know that above ISO the sensor noise will be too great for satisfactory results and they are protecting their customers. You can shoot a wider field or take longer exposures but not ramp up the ISO past those settings.

They are letting customers know that a 5 VDC USB connection will not provide the needed power for the device. Clearly they have had customers who have had problems and they were using a USB power source. It is like the bread toaster that has a warning label stating not to use it in the bathtub.

When I last looked at the EdgeHD 9.5 there were few adapter options than for the other SCTs. Third party companies go by volume of sales in producing components and in the past the 9.5 was evidently not as popular as the 8 and 11 OTA. In my case I was looking at it in terms of astrophotography and not purely for viewing. At least in terms of sales by OPT of Celestron OTA the 8" is still the most popular followed by the 14 and then the 11 inch. This has an impact on available add-ons and on potential resale value  when you decide to sell it.

Not only will the 11 or 14 OTA be itself much heavier but it will require a heavier mount and a heavier tripod or pier and more counterweight will be needed, and it all adds up.

The 8" has a collecting area of 50 sq inches as compared to 28 square inches with the 6" one which is quite a difference. 

For transporting gear from the car there are foldup wagons and carts that have large diameter wheels and pull handles. The ones designed for hunters hauling game out of the woods would work well for moving a large scope from the car to the viewing location. Do a search on Amazon for "game cart" and you will find many to choose from. Add a pad and some bungee cords and you are good to go.

What you need is termed an Access Point and it will need 110 VAC power but acts as a repeater to extend the reach of the WiFi signal from your router. A problem I have seen with computers is that the smaller they are the smaller their antennas and the less effective they are in terms of Wifi transmission. What can help is a USB Wifi adapter plugged into the computer's USB  port and then you can adjust its external antenna for best reception. Whatever devices you get be sure that they have good external antennas.

I bought a used D610 for modification by the people at Life Pixel (https://www.lifepixel.com/Lightpixels). The D610 has live view which is very helpful for IR photography.

Mirrorless may have advantages for astrophotography with the electronic viewfinder but I dislike the EVF for use outdoors in sunlight where the brighness shifts depending on how close my eye is to the EVF. 

In general low resolution cameras have larger photosites and are more efficient at capturing photons of light. Lots of other variable but I would expect a Z6 to be better than a Z7 for astro use. I recently acquired a D5 and am curious as to how it will compare against the D850 for astophotography. One advantage of the D850 is that in APS-C or DX mode it still provides a 19MP file, much as does the Z7 camera.