The first two problems I have no idea how to start, but here's what I have on the 3rd
r = r + tv
v = (1-0,-1-1,6-1)
v = <1,2,5>
r1 = <0,1,1>+t<1,2,5>
r1 = <t, 2t+1, 5t+1>
v = (-1-(-4), 6-2, 2-1)
v = <3, 4, 1>
r2 = <-4, 2, 1> + t<3, 4,1>
r2 = <3t-4, 4t+2, t+1>
r1*r2 = 0