I haven’t kept boas, so am not entitled to an opinion.
No it is not.
It varies. I currently have 8 jags in my collection and have had 4 others in the past. 11 of the 12 had only very mild symptoms. The other, a male DCI/coastal intergrade, had fairly strong symptoms as a hatchling that manifested itself at all times, not just times of excitement which is frequently reported. He was quite difficult to feed as he either couldn’t hit the prey or couldn’t locate it after he constricted it. For the first 2-3 years it would normally take 4-6 offerings before the meal would be consumed. The snake is now 10 years old and has become fairly efficient at feeding on offering #1. However, at about 4-5 years of age his equilibrium became increasingly poor. The snake is more likely to be spotted upside down than right side up these past several years. None of the other jags in my admittedly small sample have had any noticeable difference in the degree of their symptoms over the years. However, there is enough reported evidence in other collections to show that it may get worse. And sometimes get better. But I think mostly what you get wobble wise as a youngster is what you will get as an adult.
The wobble only occurs in jags. it is related to the gene
I don’t think it matters, they all calm down.
Summertime is prime time, but autumn is popular too.
Nick obviously very good. My go to guy for carpets is Will Bird at http://www.ectotherms.net/. I’ve been doing business with Will for over a decade. He produces top notch animals from excellent lines with reasonable pricing. He’s a great guy who will provide you all the help and advice you need. He’s in it for the animals, not the money.