1.) How low is "low?" This probably boils down to personal preference, but I'm wondering how low y'all pitch yours while still having enough height beneath it for cooking and whatnot. Went stakes then ridge - hoping to find some trees on my trip this coming weekend to practice the reverse.
By having a big enough tarp to start with!
This is why I got rid of my Spinn Twinn -

I found the setup to be a pain in the butt, it just took me to much fiddlin' about to get the pitch I liked.
Yeah it was light, but no way was it a two person shelter for bad weather. Although, to be honest, it did rain a bit the night that photo was taken, and my wife and I slept dry. Note that we do not use bivys under, so we have less margin of error than you will with that fancy bivy of yours. When the rain hit I did open an umbrella and set it up to sorta close the open end and keep the rain drops off my nose as I slept.
As you can see, to get decent shelter we pitched it awful low, and had to crawl in under it. To me this is less than Ideal. I like a shelter I can sit up under.
But that entire shelter, tarp, lines, stakes and ground cloth, was less than a pound! As a solo shelter, it would probably be fine ( although still lower than I'd like it to be).
As usual, everything is a compromise.
In heavy wind, the way to pitch an A frame tarp is indeed as Bill S wrote. Stake one long side of the tarp right to the ground or very close to it, perpendicular or "across" to the wind. Then go about raising one end with a handy stick and staking that pole and corner down. The lee side can be left quite high, so you'll have room under. The wind will blow over the tarp, not through it as it would if you had pitched the long axis parallel to the wind.
Of course, you should ideally be looking for a sheltered spot! This is more important with an open tarp than a tent, but then again, with your super-bivy which looks to be a micro-tent, you may not be as concerned.
As to stakes, I find I tie off to trees and bushes a good bit, and I always carry a single one ounce aluminum snow stake -

This makes a great magnum anchor if I have a ridge line stake that threatens to pull out. The side stakes don't need to be heavy duty and anything will do, but the ridge line is critical.
This stake is also my potty trowel. Indeed, I first started carrying it because it was significantly lighter than any potty trowel on the market! Such stakes are carried by REI and are cheap. Ya might want to pick one up this week before your trip.
I can certainly appreciate needing to save a coin on gear, and I can also appreciate the need for as lighter pack!
Most of my tarp camping has been with ordinary woven poly tarps. They work very well, but are not very light.
In this tarp thread I show how to make super light yet surprisingly tough tarps for very little coin -
https://www.trailspace.com/forums/beginners/topics/120382.html
I have come to prefer a larger rectangular or square tarp that offers more variation in pitching than a dedicated A freame kinda tarp.
One last bit of advice, if you are the sort of feller that enjoys a good book, find a copy of Ray Jardines "Trail Life". You'll find much detailed info on his method of A frame tarp usage and stealth camping. It's an excellent book, highly recommended, and Jardine is all about saving coin by avoiding all the hype and expense of the commercial big dollar gear "You Simply Must Have".