if by $F(y)$ you mean $F_X(y)$ then yes (a) is correct. But you should be able to explicitly determine what $F_X(y)$ is given that $X_i$ is uniform on $[0, \theta]$. The same goes for part (b). You are given $f_X(y)$.

(c) you should know how to do, you found the mean and variance of a distribution in one of the other problems.

(d) just apply the results above.

(e) you can either try and work this out yourself or you can look it up on the web. There are plenty of derivations of this available. Working it out isn't that hard. Just think about what it means to be the ith order statistic in terms of the $X_i$'s.

(f) is like (c)