In still water the answer would be about 10 knots. With current running with the wind, 12 knots would be the better estimate. With current against the wind, first whitecaps at about 8 knots. To use this estimate most accurately, one must account for the current.

About one day. We use the estimate that for winds less than 30 kts the time is about half the speed in hours and for 30+ it is the speed in hours, so one day (24h) is the closest.

They get steeper. In terms of energy conservation: as they slow down they lose kinetic energy and build up potential energy by getting higher.

This is the definition of significant wave height.

Use the sum of squares rule: 6×6 + 8×8 = h×h, so h = 10, or solve by drawing a right triangle.

Trade wind waves. The wind speed is given as 17 kts, so the only other factors are fetch and duration, and of all listed the trades have the biggest opportunity here.

The Beaufort scale is the system that links sea state to wind speed. When this system is known and the seas do not match the waves, then the cause is usually current.

Stratiform clouds, layered because there is no vertical motion which is characteristic of unstable air.

North-northeast. Higher winds near the clouds are veered relative to the surface as there is less friction there.

High Pressure. The sinking air occurring in Highs tends to evaporate clouds and produce clear skies.

High pressure means clear skies so the temperature can drop over night to form fog (no cloud blanket to keep the surface warm). The value of dew point does not matter since it is always relative to the temp.

Whether or not it is sea fog or radiation fog. The latter will burn off; the former is less likely to.