scripting and camera question

my first question is about scripting. i made a script that will make an object move 1 space when you press the space bar, but how to i make it so it will continuously move when the space bar is held down. and my second question is how do i get a camera to follow a sphere without it rotating with the sphere? someone told me to use a configurable joint, and when i did that it stopped rotating, but the camera just fell through my plane.

{ //do something }

should say if the space is held down..

you could do a MouseOrbit script on the camera and make your player the target. if you need that script, tell me and i'll give it to you.

1st Question

function Update () {
if (Input.GetKeyDown ("space"))

2nd Question

Set up a Look At & Follow script.