Replace the game disc with an audio CD during game play. The game only uses the CD-ROM for music. The music from the audio CD will play in the menus, but not during missions.
Get the ME 262
Start a mission in mid to late 1944, then go to heavily defended areas.
Get the P-51
To get the P-51 you just have to start out in mid to late 1944. Note the missions are harder.
Take out enemy fighters
Go to the outside view of the B-17 and place the mouse pointer on the far right. A box should appear with some planes. The Americans are the planes next to the stars. The Germans are marked with + signs. Click on the German planes and take control by pressing M. Then, bail out. Use the [ and ] keys to get the entire squadron. Do this to every squadron to become fighter-free.