Space geometry

Find the area of the triangle $ABS$. Only first two coordinates of the point $B=[2;0;?]$ are given and $B$ lies in the plane $\alpha$ defined by the equation $$\alpha :2x+y-z-5=0.$$ The point $S$ is the intersection point of the plane $\alpha$ and the line $k$ which is perpendicular to $\alpha$ and passes through the point $A=[0;0;1]$.

In the following list identify a pair of planes such that the distance of planes from the plane $\alpha$ is the same as the distance between the point $A=[0;0;1]$ and the plane $\alpha$. $$\alpha :2x+y-z-5=0$$

In the following list identify a line parallel to the plane $\rho$ such that the distance between the line and the plane equals $1$. $$\begin{array}{rlr}\rho :x& =1+r,& \\ y& =1+2s,\\ z& =1+r+s;r,s\in \mathbb{R}\end{array}$$

In the following list identify a line such that the line is parallel to $s$ and the distance between both lines is $\sqrt{5}$. $$\begin{array}{rlr}s:x& =-1+t,& \\ y& =2t,\\ z& =2-t;t\in \mathbb{R}\end{array}$$