If it doesn't rub, you're all set. IIRC 6 to 8 clicks is what's in the workshop manual.
If you replace the front left only, you'll probably end up with uneven braking, as one caliper clamps before the other. With the left disc being new (ie. thicker) it'll meet the pad before the other side does. As you keep pressing your foot down to get the right side to clamp, it'll now be pressing harder on the left side, and so on. So you'll prob end up with the car steering left every time you hit the brakes.
It has been a while since I changed the brakes on my R32 but I don't remember there being any way to tighten one caliper in particular. You'd need to be able to offset the pistons, which you might be able to do when you bleed the brakes after changing the disc. Actually no, I don't think you can because you cant adjust individual calipers on a stock car.
Anyway, I highly recommend changing both, but I guess it depends on how worn the right side is. If the thickness is fairly close, you could be in luck. If you REALLY wanted to only change one, you could have the new one machined to reduce its thickness to match the right hand disc.