Translation and equivalences 

2 (d)
all X,Y (b(X,Y)->s(X,Y))

2 (e)
all X,Y (s(X,Y)->s(Y,X))

2 (g)
all X,Y,Z,T (cousin(X,Y) <-> parent(X,Z) & sibling(Z,T) & parent(Y,T))


Herbrand interpretations and models

1.1a
U={0,s(0),s(s(0)),...}
B={odd(0),odd(s(0)),odd(s(s(0))),...}

1.1b
U={car , owner(car), owner(owner(car)), ...}
B={has(s, t) | s, t \in U} \cup {happy(s) | s \in U}

1.1c
U={a}
B={p(a)}

1.2
I1 = {}
I2 = {odd(0)}
I3 = {odd(s(0))}
I4 = {odd(s^n(0)) | n \in {1, 3, 5, ...}}
Only I4 is a model of the formula.

1.3
The only Herbrand interpretations are {} and {p(a)}, none of which is a model.
But there is the following non-Herbrand model:
|I|=natural numbers
a_I = 0
p_I = {<1>, <3>, <5>, ...} (p means "odd")
This is possible because the formula is not in CNF.

Normal forms
The CNF form is: -p(a)&p(c)
A Herbrand model is: {p(c)}