Let's complicate #2 above further.
Business A is, by definition, an insider.
If Business A guarantees credit for Business B, it's a credit extension (regardless of ownership). So obviously that credit has to be on included in Business A's 15% maximum. If it occurred, would a reduced rate on this loan represent a violation simply because Business A, an insider, is a guarantor, even though their ownership % does not make them a primary owner?