The scaffolder has duties to erect safely and to ensure scaffold is safe at handover but beyond this I see no other duties for registers etc. Only the scaffolder is undertaking construction work as defined and is AT WORK Bob

I would answer your questions as follows: Yes, every 7 day period. A competent person, ideally, but not necessarily from the scaffold company who erected it. Yes, even though it is not notifiable under CDM criteria (30 day contract duration or 500 'man' days). Just because it is a domestic client does not devolve or eliminate the need to undertake scaffold inspection which may compromise safe working by anyone who may use the scaffolding.