I think you're on the right track. These can get confusing.
CONTACT with an official in the restricted area is a Sideline Interference PERSONAL FOUL charged to the HC, no matter who you run into. The second time you run into someone, it's a personal foul against the HC and he is ejected. This is not combined with any other sideline penalty or any other unsportsmanlike foul.
NON-CONTACT sideline penalties (Sideline Warning/Interference) progress to 1) Warning, 2) 5 yards, 3) 15 yards and unsportsmanlike charged to the head coach, no matter who is in the white.
Regular Unsportsmanlike fouls are charged to the individual who committed the act.