To find the x-intercept (point A), set y=0 in the equation 4x − 2y = 8.

So, point A is $(2, 0)$.

So, point B is $(0, -4)$.
The coordinates of A and B are $\boxed{A(2, 0) \text{ and } B(0, -4)}$.

(2) The coordinates of C and D.

So, point D is $(-1, 0)$.

So, point C is $(0, -1)$.
The coordinates of C and D are $\boxed{C(0, -1) \text{ and } D(-1, 0)}$.

(3) The gradient of $4x - 2y = 8$.

The gradient $m$ is the coefficient of $x$.
The gradient of $4x - 2y = 8$ is $\boxed{2}$.

(4) The gradient of $x + y = -1$.

The gradient $m$ is the coefficient of $x$.
The gradient of $x + y = -1$ is $\boxed{-1}$.

(5) The coordinates of E.

Equation 1: $4x - 2y = 8$
Equation 2: $x + y = -1$

The coordinates of E are $\boxed{(1, -2)}$.

(6) The values of $x$ for which the lines are increasing or decreasing.

For the line $4x - 2y = 8$, the gradient is 2 (from part 3). Since $2 > 0$, this line is increasing for all values of $x$.
For the line $x + y = -1$, the gradient is $-1$ (from part 4). Since $-1 < 0$, this line is decreasing for all values of $x$.
The line $4x - 2y = 8$ is increasing for all $x \in \mathbb{R}$.
The line $x + y = -1$ is decreasing for all $x \in \mathbb{R}$.