I actually answer 1 and 3 in this post here As for 2, I generally think that foals really just need milk, warmth and affection to thrive so as long as they are getting these they should develop without issue. In fact, since humans tend to be more competent all around, I would think that a fluffy raised by humans since birth would actually be far better off than a fluffy raised foal.
With regard to #4, I would think that an average fluffy is very protective of its offspring to a point. They have the instinct, not programming, to abandon their young if the possibility of rescue/protection is non-tenable so the mother will save herself; the whole she can always have more children instinct. Now, there are some fluffies with underdeveloped maternal instincts who will abandon their offspring at the smallest provocation while there are ones with overdeveloped maternal instincts who would literally die for their young; both of these were not intended by HasBio.
With #5, my headcannon was that pregnant dams were never meant to be sold except to breeders. Fluffies that were commercially sold would have been sterilized to Hasbro could keep a monopoly of fluffies. They would have advertised foals as the “LOOK MY PET IS AN ADORABLE BABy!” type pitch.
As for Babies on FluffTV, it is mostly just stock footage of babies but framed in such a way to make foals seam really appealing. This would be to try and get both mares and small human children who are watching to want to get a cute baby fluffy. There would also be adds in between the footage advertising the local Fluffmart “where you can buy your very own foal” or telling owners of take their fluffies to official licensed HasBio breeders if the mare wants to have her own. And of course, there would also be adds for official Hasbro foal raising merch which would be framed in such a way to say “only good mammahs have this stuff so their baebehs can be the bestest so they should ask their mammah or daddeh to get it for them.”