The Part of Fortune traditionally acted as an indicator of good health, a more modern interpretation is as an indicator of prosperity. The house position should indicate the area of life where you can contribute to your health and prosperity and the sign will indicate the way in you will approach the goal. In the third your prosperity can come from communications, siblings, neighbours, education, etc. Scorpio suggests that a transformative, powerful and passionate approach is likely. The conjunction with Neptune suggests as you say that there could be an intuitive and spiritual dimension, though Neptune can be rather negative, representing self deception and dreams and fantasies – so you might make your living out of writing science fantasy novels or find that whatever you try to do to boost your prosperity turns out to be illusory. In other words, tread carefully.
The Part of Fortune changes if you progress a chart or do a return chart, as its based on Ascendant, Sun and Moon positions. Whilst I might look at transits or progressions which aspect the natal Part of Fortuna, I don’t think I would really bother with the progressed Part, certainly not as a major factor in analysis. I don’t recall anyone using the progressed Fortuna in a major way. If anyone has seen work on the progressed Part I think it would be interesting to post and let us know.