Just joined this site and saw your query about Knockando House. The Moray history sites suggested by other readers are your best bet for its past.
Basically it was (and is) the "Big Hoose", home of the local Estate Owner - in this case Knockando Estate. In the 1940s/1950s it was in the hands of Major Whitelaw (a relation, I believe, of Willie Whitelaw, who was a Conservative Cabinety Minister in the 1980s). After he died it passed into the hands of the Wills family (of tobacco fame). Not sure of the current owner. My father worked for Major Whitelaw in the 1950s. The Estate owns most of the land round about, farms and forest and moorland. The East Mains and West Mains farms are what elsewhere would be called the Home Farm of the Estate.
I notice one of the names you are interested in is Margach. The local Village Hall (or Parish Hall, I suppose in Knockando, there being no village as such), is called the Margach Hall, presumably after a benefactor.
Knockando still has a Primary School, a Church (and Graveyard), three Whisky Distilleries (Cardow, Tamdhu and Knockando - the latter is still usually called "Gilbeys" locally, after the company that owned it for most of the 20th Century, and Cardow is usually CARDHU once it is bottled). Dhu is the Gaelic word for Black - Cnoc or Cnocan is a small hill, so "Knockando" is a small black hill or hillock. Locally there are several similar Gaelic place names (including Tamdhu, which is basically the same thing) and the numerous Anglified versions of Blackhillock.
Regards
Alasdair