More puzzles!
So I heard you like Bioshock Infinite...

This thread is made so I can enter Mew2's giveaway event thingy here.

All the regular rules apply. No cheating, sharing, or hinting.

Solutions

The answer to the question is ∞
To decipher hdzbfezbfv3mb1h?/oqe.gtkhckfgo.yyy just reverse it and shift it by 2 in the alphabet to get www.mediafire.com/?f1zk3tdzxcdzxbf
Download the file, change the extension from .exe to .wav or something else and listen to it. At the end of the track there is a length of garbled noises. Reverse that particular area and use a sound visualizer to decrypt the code to get the message 6LfP8 leading to the giveaway.