Questions about a cross-platform, uploading plug-in

I have read

I would like to develop a plug-in that works on Linux, Mac and Windows which uploads a picture of the waveform displayed in audacity to a website automatically. Also, tag information and an average db level should be uploaded. (At the moment my concept is to use Coppermine or similar for the website which stores the pictures.)

Does this sort of thing sound difficult? Do I need to use C++ to develop the plug-in? I am only moderately techie and although I did a bit of C++ way back when I haven’t done what I consider hard core development. I seek the simplest way to achieve the aims stated, of course.
Thanks, Darren