@Garanwyn, you are exactly correct with your formula and chart:
formula
CP=(base CP for stars) + floor(attack * 0.35 + defense * 0.28 + health * 0.14) + (special level - 1) * 5
chart
1* Base CP: 0
2* Base CP: 10
3* Base CP: 30
4* Base CP: 50
5* Base CP: 90
I put that into an excel spreadsheet and if I put in the base value, attack/def/health and special level for a hero, it always give the exact power for that hero 
However when calculating total team power, you can’t just add all 5 hero powers because there is a value for each TROOP.
I found exactly what is used to get the additional power each troop adds to team power, it is:
1*=10+troop level
2*=20+troop level
3*=30+troop level
4*=40+troop level
So a 4* level 8 troop = +48, a 1* 1 is +11, a 3* 3 is +33, etc…
Now you can add all 5 heroes powers and all 5 troop powers together to get team power.