MANU

1. You can make the maximum from wind, in this case L15 = L11, L12, L13, L14 (MAX) if you want.
Or :

L1 WW+HP (HYD)
L2 W+P+T+D (OPE)
L3 W+P+T+D+Win1 (OPE)
L4 W+P+T+D+Win2 (OPE)
L5 W+P+T+D+Win3 (OPE)
L6 W+P+T+D+Win4 (OPE)
--------------------------
L7 W+P (SUS)
L8 T+D (EXP); just created to generate HOT SUS
L9 L2-L7 (EXP)*
L10 L2-L8 (HOT SUS)*
--------------------------
L11 L2-L3 (OCC)*
L12 L2-L4 (OCC)*
L13 L2-L5 (OCC)*
L14 L2-L6 (OCC)*

L15 L11+L7 (occ)
............
L18 L14+L7 (occ)

L19 L15,...,L18 (max)


2. You can have small diferent between wind case +X and -X, how much depends by system.

3. Why because you not have a symmetric system and a small difference in your pipe configuration have effect in your calculation results ( for see this influence just make a small and simple system and you see the difference).