An opamp circuit schematic

a): An answer:
$\frac{i_{diff}}{v_{in}} = g_{m}$
b): An answer:
$\frac{i_{o}}{i_{i}} = \frac{βfe}{βfe + 2}$
c): An answer:
$\frac{i_{x}}{v_{in}} = g_{m} \frac{βfe + 1}{βfe + 2}$
d): An answer:
$r_{in} = R_{E} (1 + βfe) + \frac{βfe}{g_{m}}$
e): An answer:
$a_{opamp} = \frac{v_{out}}{v_{in}} = - βfe \cdot R_{C} \cdot g_{m} \cdot \frac{βfe + 1}{βfe + 2}$
f)
g): An answer:
B
h): An answer:
$r_{in} = \frac{2 βfe}{g_{m}}$