A lot of their feeding and care instructions are the same as PPP. The cage requirements they say is also the same as PPP.
Gliders do not need to be kept in small cages until they are older. The biggest glider safe cage you have room for and can afford is always best.
I would recommend you choose an approved diet (from the Gliderpedia diet tab)and not follow their plan(they will try to "Up-sell" you their crappy food and supplements).
Their web site says they are "USDA" breeders but that does not mean they are not mill breeders or that they are good breeders.
All that means is that the gliders have a minimum cage requirement "for Breeders"
Which is 1' x 1' x 1' cages, and have passed sanitary inspections.
There are some breeders that go way beyond those recommendations, to their credit for the health and well being of the gliders they keep as breeders and the joeys they raise for sale, But it is not the "norm" for the mill breeders who are supplying the "Mill Brokers"(aka Gliderpets) with animals.
The vitamins and minerals should be added to the "Nectar replacement" staple diet you choose...not sprinkled on food or added to their water.
If you do get joeys from them, I would have an exotic vet appointment set up the same or next day for fecal testing and wellness exams and make sure to test again after 30 days, the next generation of parasites can hatch out by then.
But I would really encourage you to look elsewhere for gliders. Even if you ask the right questions, you may not get the right answers(they like to tell people incorrect OOP dates) or they will tell you what they think you want to hear.
They are master salesmen. And like PPP they will tell you that "Us forum folks don't know what we are talking about" to steer you away from any info that will conflict with what they say.