Huddling Prior to a Free Throw

[Kansas Ref]

All of this huddling up prior to a FT [and after a FT] is largely driven by what players see on TV games. I recall this activity first became "fashionable" to do by Duke teams of the 1990's (or maybe other less renown teams were doing it and it only became apparent since Duke is on TV so much). At any rate, your rules knowledge is accurate in this area--as you've stated in your post: event #1 = warning for DOG, event#2 = cup of T.

Regarding contact on the FT'er (A1): most coaches hold that the FT'er is in a vulnerable position while in the follow-thru part of a FT try--the risk of injury is great when the arms are extended upward and you have (B1) forcefully bumping into the groin of A1 in a box out attempt. A1 has no means of protecting self --so we call a common foul if such contact occurs prior to ball hitting the ring.