The major cataracts of the Nile are far upriver, well south of the area of the Nile the Egyptians usually navigated in.
They dug irrigation canals to carry water from the Nile.
Because it was a sourse of life
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Carry goods for trade
irrigation
Yes - The Nile is nearly as good as the only source of water for Egypt.
The cataracts did not impede the Egyptians from crossing the Nile.
Yes
irrigation system.
Camels by land, and boats on the Nile
To measure anything - one use was to record the annual Nile flood levels.