My advice:
1) Attributes:
Use one Target Number (TN): 15
Humans choose 3 Prime, 2 Secondary, and 1 Tertiary Attribute. Demi-Humans choose 2 Prime, 2 Secondary, 2 Tertiary.
Bonus to rolls are: Prime (+3), Secondary (+0), Tertiary (-3)
2) Checks:
CK should only ask for checks when they are...