Newbie Python questions

[LessPaul]

I recently discovered Python and see it as a great language to use for
personal projects (and more). I made my living for over a decade as a
coder in C, C++, ADA, Fortran, and Assembly before moving to systems
engineering.

I'm now retired, and would love to code again. I see Python as the
perfect language to get a good program working in a short time. My
question is in regard to GUI platforms. My primary target would be
Windows, but I would also like be able to support Linux and Mac
versions if possible. I'm also interested in using a system that also
has support for pure C++ applications. As such, and after reading many
web pages regarding Python GUIs, I believe I have the candidates
narrowed down to pyQT and wxPython.

The first question -- how steep is the curve to become proficient with
the above GUI packages? If the answer is "not very" then there is no
need for the following questions as I can try both on for size to see
which I like best. However if it is a sizable investment in time, I'd
like to maximize my efforts and choose the one I'll end up using in
the end.

The biggest hurdle I can see is the cost of the QT licence for
commercial software, though apparently it can be acquired for a
reasonable price via the BlackAdder package. Does purchasing the
BlackAdder also include the needed software support for C++
development? Does the BlackAdder purchase also allow for licence of
standard C++ apps?

Since there appears to be no commercial licencing fee for wxWidgets/
wxPython, the last question is what do I gain from going QT over wx?
I've seen great applications written with both (on my computer I have
the wxPython Digsby and the pyQT apps "Mnemosyne" and "Anki". All seem
to be solid.