complicated question from a past paper that i dont understand

An aeroplane flies at a constant spead of 800 kph in a straight line from

(-100,-200) to (300,1000)

x axis and y axis are east and due north

1) find the equation of the straight line.

I got y= 3x +100

2) find the direction of travel of the aeroplane as a bearing, with the angle correct to one decimal place.

i HAVE NO IDEA

3) There is a beacon at (0, 200) which has a range of 100km

Find equation of straight line

I know equation is (x-a)^2 + (y-b)^2 = r^2

but is the radius 100??(Thinking)

4) find the points of intersection of the straight line and the circle, hence find the time during which the aeroplane is within range of the radar station in minutes to one decimal place.

HELP???

Thanks