As none has approached to create a guide for this game, I intend to make one. If I had any wrong information, feel free to obligate.
Current game version: 1.4

[Mouse Schemes]
Mouse Button 0 (Left Click) - Shoot Primary cannon/Drop bomb(in drop mode)
Mouse Button 1(Right Click)(Hold) - Focus on target

[Keyboard Schemes]
W/S - Pitch Up/Down
A/D - Yaw Left/Right
Space - Accelerate
Z - Control Tail gunner
B - Bomb drop mode
Q - Focus on target(same as Right click)
L.Ctrl - Shoot Primary cannon/Drop bomb(in drop mode)
C - Shoot Secondary cannon (20mm)
R - Rocket
T - Torpedo
V - Missile view
L - Planes list
N - Next plane
P - Pause game
Esc - Menu

Join a mission. Then go to Settings. Controls. under Cotroller, click Remove. Now the game will show K+M options.

All nations have same Airfield/Mainmenu.
From left:
1. Base Overview: Shows how many base structures, planes, pilots you have.
2. Manager Skills: Tutorial menu. Choose one of many to learn a skill. You will get Medal reward which you would need to when launching naval mission.
3. Pilots: Crews menu. Train them to improve their specific skill. (Note: you need to recruit one when your crew is injured)
4. Planes: List of planes you own in that specific nation. (Note: only 'Ready to Fly' marked planes can be taken to mission)
5. Choose Mission: Launch a mission.

Sorry you can't right now. Click Exit game from Settings menu. Then Start game again and choose.

At current game version, you need to move the mouse cursor to the center of the screen to activate the mouse control. Once activated you can use the mouse without any further problem.

When main objective is done, stay on mission and complete the secondary objectives. That will drop you more rewards. Complete all the tutorials to earn Medals for Naval missions. You can purchase War supplies and Premium mode for better outcome. Also activating Hardcore mode from Settings will grant you +10PP per mission(although this disables auto-aim).

When they are close hold Right Click button to activate auto-aim. Then use your 20mm cannon (C default).

They can shoot you if you're flying above them. When attacking a bomber from behind try flying under him. I guess that will help you.