Cool that you're getting your clutch issues sorted out. I don't know why the end-play isn't addressed in the Kyosho instructions, as reducing the end-play has a significant effect on the life-time of your thrust bearing.
Its quite easy to set the end-play once you've done it a couple of times. Keep adding spacers until you get no fore-aft movement when you push-pull the clutch bell, then remove one spacer and check to see if you can just say move the clutch bell by pushing-pulling it. There should just be a little bit of movement, approx 0.1mm.
You don't need so much grease on the thrust bearing, any excess will be thrown off by the rotational forces once your car is running. Actually when I have freshly lubed and greased the clutch bearings, my clutch bell will only spin for about 3-4 seconds - all depends upon which grease you use. One of the best is Mugen Super grease, as it really sticks and doesn't fly off so easily.
The important thing is to grease the bearing after each days run and clean and lube the two metal shielded bearings with degreaser and then WD40. You bearings should last a heck of a long time as long as you do your maintenence.
Cheers, Mark.