Cushie, an easy word, has acquired several meanings, none having anything to do with biblical Cush (Kush).

Cushie- nickname for a cow (perhaps more understandable if it is known that cow is 'coo' in many parts of the UK).

Cushie (cushy)- an easy job. Cushie in the UK and Oz land, cushy in the States. The OED says the Army picked up the word in India, from Hindu 'khush' (see post by Graham). Probably picked up in India long before WW1, I believe, Graham, but I haven't had a chance to check on it. Soldiers, clerks and civil servants were in India for a long period of time, starting in the East India days.

Cushie- a redhead, esp. in Australia. Also heard in Canada. An American woman related to a prominent politician has that nickname- can't remember who, but is white. I'm sure some Mudcat will know.

(I'm sure someone will bring up macushla- )

Cushie- the wood duck, northern England dialect, also applied to a dove (from cushat).

Cush- to bash on the head. Variant of 'cosh.'

Cush, Geographic area-
In the UK, usually refers to the Hindu Kush and the people there, because of campaigns during the Raj.

Biblical Cush- Not certain what is referred to here. Could be Ethiopia, but other scholars place it in Arabia or Babylonia (the 'Kassites, in one spelling). Very dubiously related to the Nubians to the south of Egypt. The Bible is no help. The wackypedia contains much nonsense on such subjects.

Most of the very few blacks in England in the 17th-18th c. were kept for curiosity value by the very wealthy (some were east Indians, also often called blacks); Grab is correct. In the 19th c, a few would be found in seaport towns.