Question 1. Ans:
Here in the above circuit, transistor Q8 with transistor Q9 forms current mirror circuit. (generally the current mirror consist of two matched transistor with their base and emitter connected together where one of these transistor connected as diode by sorting its collector and base.)
Question 2. Ans:
the transistors Q1 – Q3, that is Q2 – Q4 are in complementary Cascade arrangement. This pair also helps to create virtual ground between inverting and non-inverting inputs in the case of differential mode input signal because it's base in not directly grounded.
Hope it will help you.