The most commonly used layout for CD.

Presents represent crystals.

Buff size doesn't matter much. In my experience stacking minions doesn't worth the effort, less chance of them going down if they're spread out. Always keep the buff/minions off the stone circle. That's about the safe distance from ogre swing range.

Build auras roughly halfway between buff and the crystal.

Most important part of the whole run is to roll wheel dmg-s (3x swords) with jester as often as you can. For the first roll in a wave i always wait until the first copters spawn in. Up buffs ASAP.

#4: My favorite spot to stay during the wave.

The 4 archer + mage + spider is my solo setup, 4k stats. I tend to sit at the marker after upgrading buffs, i don't bother with upgrading anything else.

Depending on stats / experience in rolling you can build less archers (or more)

I don't know the minimum required stas for CD, I did it with 2k builders. (6 archers / buff, gas on each buff to protect them from djinns and a few reflects)