2.1 distance You can simulate distances of 0 to 3 arcseconds. If distance is zero only one diffraction image is calculated. If you chose another distance two diffraction images are calculated and added. The luminance of second star is always equal or less then luminance of start one. Chose pixel dimensions of your ccd sensor.
Bigger pixels mean less resolution.
For an given pixel you have to change focal length to change pixel resolution. You have five bars to change spectral function of received light. For simple calculations you are using only one wavelength of 550 mn. But your star images contain more than one wavelength, so received diffraction pattern are more complicated. If you are using a ccd sensor you have to simulate ccd sensivity.