Which of the following statements are true with respect to the blowfish algorithm?

Which of the following statements are true with respect to the blowfish algorithm?

i) Provided key is large enough, brute-force key search is not practical, especially given the high key schedule cost
ii) Key dependent S-boxes and sub keys make analysis very difficult
iii) Changing both halves in each round increases security
iv) Blowfish has improved avalanche effects