You can use a selvage / bias orientation on each seam and stretch will be similar. The thread also comes into play, minimizing stretch in the seam.
Circular vs. Vertical and Hybrid orientation of seams:
It depends, our 6 person and 8 person are a hybrid as is the 3 person (but a different orientation). The BCS and the 12 shown were vertical.
You probably setup with less stakes easier on vertical, but for winds above 25 or 30 I'd think it's best to use them all anyway. On the circular, you don't need to use all stakes, but I usually do.
The ridges (vertical seams) add some structure, but there are other ways to do this, and they also create some challenges. I would consider guyouts just as important.
Height, is mostly a pole problem. FWIW the BCS is very tall to it's footprint and handles wind very well. If you are planning to use trekking poles, stick to about 6 ft.
Regarding cat cut, you probably need a lot less, 3" would be more what you would need if you were going square / mid style. You could take two panels, pin them how you want into the shape and see how much they droop, and then make that your cat cut. My guess, is you will be closer to 1.5 ", depending on fabric.