Couple of questions

[fearo]

Well I got my car up and running, thanks to some of you guys suggestions on my diff problems, thanks!

However, with finding a solution for one question, comes a couple of new questions .

first thing, i set up the slipper meticulously and so far it's going great, but there's one thing i've never found the answer too: How do you know if the diff is tight/loose enough. Right now the diff is tightened about 1/2 turn from max, and I setup the slipper from there. Should I try loosening the diff some more or would it be best to leave this be?

Secondly, a motor/power question. I run a Team Orion 3900kv motor with a sensorless ESC, gearing 24/80. The motor does not 'cog' or anything. When I hit the throttle from 1/4 to full, it accelerates perfectly...
BUT: When I hit the throttle like 1/8 of the way (car barely moving), the car makes a weird trembly/stuttering sound. Is this normal, or is this a sign from something that's not right? Overgeared? Diff too tight?

Thirdly, I started reading up on gear mesh between the spur and pinion. At first, because I'm a complete newbie, I had the pinion and spur crammed onto each other as tight as possible. Now I've done the 'paper trick' and also listen to the sound of the car, when placing the pinion further away from the spur. I think I found a good solution, but I've noticed that the car does 'rattle' a bit if I stop accelerating and the car nearly comes to a halt. Again, is this normal?
Thanks, guys.