A lot of your questions will be answered by the videos above, so I will just give you some of my personal experience/advice/opinions.
I don’t have a spider, and probably won’t get one just because I don’t generally like their patterns. But I do have a champagne combo. I have only seen the tiniest hint of a wobble when he was about to strike when being fed once. He has no head tilt when holding his head up, and I sometimes forget his morph even wobbles because he moves just like a normal BP.
I have noticed that inbreeding might play a role in how bad the wobble is as well. I have also noticed that spiders tend to have things like the head tilt a lot more than other wobble morphs. That is either because there is more inbreeding in the ones I have seen, or the wobble may just very in each morph that has it. Rule of thumb with a lot of issues in animals is that you have a higher chance of the severity increasing the more you inbreed. Like kinking in snakes, as well as bug eyes and duckbills. Another thing that most people follow is to never breed 2 wobble genes together. Like Spider+Spider, spider+champagne/woma/sable/spotnose. It all increases the chances of severe issues, on top of the fact that most of them are potentially lethal combos. There are people that breed those combos together despite the high risk, and I personally don’t plan to purchase from anyone that does. I also never plan to buy a combo of two wobble genes so I am with you on that.
Lack of stress is another thing that helps keep the wobble under control, even in snakes that generally have a pretty bad wobble. If you get a wobble gene from a breeder and they said it doesn’t have wobble, and when you get the snake it clearly does. Chances are the snake is highly stressed and will take a bit to get used to everything and go back to having little to no wobble. When I got my champagne however, I asked to breeder if him or his parents had any wobble, and he said he never seen any wobble in his champagnes. He also never showed signs of a wobble when I got him home. Even after the shipping he went through he didn’t show signs.
If you do ever get a wobble gene, and you don’t want a bad wobble then I suggest asking the breeder if their snakes have any wobble, as well as ask how closely related all of them are. Most of the time a reputable breeder will tell you the truth.
Also, here are a couple pics of my Champagne Banana Pastel het VPI boi Akira;
The first one I just took a bit ago for a closeup of his little eye stripe, and the second was not long after I got him.