is it possible to export the whole of my project in only one flash file which is gathering ALL the assets?
Yes. Just click (or select to) embed all the tiles in the output.
https://ggnome.com/doc/pano2vr/5/output-flash/
https://ggnome.com/doc/pano2vr/5/output-flash/
Number of embedded levels at startup – Set the number of levels that will be embedded in the SWF.
MfG, Thomas