To unlock those tracks you have to finish the game on any difficulty. You will unlock the music player and tracks of Ace Combat: Assault Horizon Legacy
How to unlock Pak fa
How you will unlock the Pak fa is by completing the last survival mission.
General Gameplay Tips
Unlocking weapons for every plane needs you to rack up your plane's kill rate. The a lot of kills, the faster you will unlock new weapons for your required craft.
Hop into the 'Options' menus and you'll modification the management settings to Classic - this makes the controls play a lot of just like the original games.
Not all planes are unlocked by buying them through the campaign mode. Some will not be on the market till you've got compete through all of the Survival and further Missions.