It is known that a nondeterministic input-driven pushdown automaton (IDPDA) (a.k.a. visibly pushdown automaton; a.k.a. nested word automaton) with n states can be transformed to an equivalent deterministic automaton with 2^Θ(n²) states (B. von Braunmühl and R. Verbeek, 1983 [8]), and that this size is necessary in the worst case (R. Alur and P. Madhusudan, 2009 [4]). This paper demonstrates that the same worst-case 2^Θ(n²) size blow-up occurs when converting a nondeterministic IDPDA to an unambiguous one, and an unambiguous IDPDA to a deterministic one. In addition, the methods developed in this paper are used to demonstrate that the descriptional complexity of complementation for nondeterministic IDPDAs is 2^Θ(n²), and that the descriptional complexity of homomorphisms for deterministic IDPDAs is 2^Θ(n²).