The parabola y^2=8x has a focal chord PQ with P=(18,12).

Here $4a=8$, so $a=2$, with points $(2t^2,4t)$. $P=(18,12)$ corresponds to $t=3$. For a focal chord the parameters satisfy $t_1t_2=-1$, so $Q$ has $t=-\tfrac13$, i.e. $Q=\left(\tfrac29,-\tfrac43\right)$: (A) is true. A focal length is $x_1+x_2+2a$, so $PQ=18+\tfrac29+4=\tfrac{200}{9}$: (B) is true. The tangents at parameters $t_1,t_2$ meet at $(2t_1t_2,\,2(t_1+t_2))=\left(-2,\ \tfrac{16}{3}\right)$, which lies on the directrix but is not $(-2,6)$: (C) is false. The normal at parameter $t$ is $y=-tx+4t+2t^3$, i.e. $y=-3x+66$ for $t=3$, cutting the $x$-axis at $x=22$, not $20$: (D) is false.