Rendering terrain only with GPU

This is not about generating plane geometry and then applying a shader on it. Instead, I want a big single flat plane, then apply a shader on it.

The vertex shader has a uniform vec3 realPlanePosition and calls a height calculation function:

// Vertex shader code

uniform vec3 realPlanePosition;

varying vPosition;

float heightCalculation(vec2 verticePosition) {
    // Just for pseudo-code (more black magic append here).
    return magicNoise2D(verticePosition.x, verticePosition.y);
}

void main(void) {
    vec3 vPosition = position;
    vec2 verticePosition = vec2(vPosition.x + realPlanePosition.x,
                                vPosition.y - realPlanePosition.z);

    vPosition.z = heightCalculation(verticePosition);

    gl_Position = projectionMatrix * modelViewMatrix * vec4(vPosition, 1.0);
}

In my plane update code, I just change realPlanePosition with player position, for example. The plane moves on (x, z) (X rotation: -PI/2.0). The only thing the vertex shader updates is the z (due to plane rotation) value of gl_Position.

Is this good practice? Also, how do I detect collisions with it? And finally, how can I control other terrain objects' generation (rocks, trees, ...)