CBG is the precursor, the weed has either CBD synthase or THC synthase. A given strain of weed can produce THC, CBD, some combination, or if deficient is synthase, only CBG. The reason for gene sequencing is to find a weed that is deficient or polymorphous and work from there, such as back-cross methods. That would be my guess. Gene sequencing method would for example take 2000 seedlings of a polymorphous strain, mince and sequence, find one plant with desired sequence, and use seed breeder techniques. Another possibility is they could be using cell culture and direct DNA manipulation. I do not know, they do not disclose this to anyone not working for them. CBN is an oxidation product of THC. Weed does not produce CBN.
As for amount, for example if I take 0.5 g which is 500 mg and my weed is 10%, then my dose would be 50 mg of CBG.
I was using fresh non-dried flower because that is all I have right now, but my desktop vape is meant for party use, means it has a pretty huge chamber. My estimate is last night I took around 75 mg of CBG, my estimation of potency is based on CBG being alpha2 adrenergic central acting, which drops your pressure, and mine definitely did. Don't worry, if you feel faint, just lie down. So far my tinnitus is holding steady at 3/10 for the entire day.
I just checked their website. It seems their price is excellent. If you are not USA based, then that is where the problem arises. For example Canadian prices for CBG are about 6X the Lazarus price, so Canadians get cheated. The USA price is around $1 per day and Canadian price is around $6 per day. So $360 vs $2000. If you are on limited budget, as most people are, this is very significant. One of my friends lives on $US13,000 per year, so take $US2000 out of that and she can't afford to live. Take $US360 out of that, and she could manage. With a social network, she can get weed for very little, by trading skills (and I don't mean her body).
Fortunately, my woman friend does not take CBG, regular weed is fine for her, she does not have tinnitus. This is what is called social injustice.