Replacing ball joints

hi guys
my main dealer reckon they have replaced the drag arm on my series II Disco. (2000)
the guy who did the MOT for me reckons that the other ball joints need replacing as well. Getting under the vehicle, the dealer has definitely renewed the arm/rod nearest the front of the car. So the ball joints that need replacing are at the rear of the front wheels.
a) are these ball joints replaceable on their own or do i need a complete new track rod inc. ball joints
b) is this rear arm definitely called the track rod?
c) how easy is to do these yourself?
sorry for the dumb q's but you've got to start somewhere!
cheers
W

The rod at the rear, that connects the hubs is definately the track rod - the ball-joint at one end is permanently fixed, and the other unscrews for adjustment. This would be replaced as a unit.

To replace this, do as follows:

Secure the vehicle and centre the steering.
Remove the front wheels and jack the front if you want, but this isnt necessary.
Undo the nuts on the balljoints and use a separator to remove the old rod.
If you dont have a separator, undo the nuts just to the ends of the threads and hammer the nuts to separate the joints.
(The reason for hammering the nuts, is that if you cant get one off, you can do it up again and drive to a garage)
Replicate the langth of the old rod on the new rod by measurement and physical comparison.
Stick the new rod on and do up the bolts to the required tork.
You should prolly get the tracking checked at a proper place, especially if it was out beforehand.