(i) In a book, a problem on fractions is given as 

$$\frac{1}{3\frac{1}{5}} - \frac{2\frac{1}{4}}{9} + \frac{3\frac{5}{8}}{a} + \frac{\frac{4}{7}}{4\frac{4}{7}}$$, 

where the denominator a of the third term is not printed. The answer is given to be 2. What is the missing denominator a? 

(ii) Simplify $$\frac{1}{3 - \frac{1}{2 - \frac{1}{\frac{5}{7}}}}$$ and let the answer be $$b = \frac{p}{q}$$, where p and q have no common factors. 

(iii) Find the value of $$\frac{1}{a^2} + b$$.