Classical Music Puzzle (lvl1+) (hints) (ended)

Hi :)
I have some leftovers from the Humble BANDAI NAMCO Bundle I really don't need so I decided to make a puzzle. I recorded the beginnings of a few pieces I can play on my electronic organ and I am curious how many people will solve this. :D

Please be nice, it's my first puzzle and I know there are some mistakes in the recordings, I did my best.
So, giveaways for

• Platformines
• Ace Combat Assault Horizon - Enhanced Edition
• ENSLAVED™: Odyssey to the West™ Premium Edition
• Dark Souls™: Prepare To Die™ Edition
• Beware Planet Earth!

Link to the puzzle

I know, may be too hard for those games.. well. Nevermind. :) Giveaways end on September 1st, 12:00pm.

EDIT:
First hints, as after two days only 4 people managed to solve the puzzle. Bach seems to be the problem.

• Q1
• Q2: Not a prime number. The digit sum is 18.

EDIT:

• Q4: Was used before the opening scene of a movie by Stanley Kubrick.

EDIT:
Ok, time's up. Solutions can be found here.