* Licensing - if you use one of the installers (for OSX or Windows) you're presented with the GPL3 as part of the installation process.
* Mac OSX package (and to the same extent, the Windows installer) - Mu comes with everything bundled in so you don't have to mess around installing a bunch of stuff to make it work. We did it this way after asking for feedback from school network administrators who always said some variation of "make my life as simple as possible". Mu is only just less than 4k lines of Python so, you're right in thinking that the rest of the installer is Qt and a bunch of other stuff (like Tk/tkinter, needed for Python's turtle module to work, something many teachers have told us they need). We also bundle PyGame, iPython, Matplotlib, Numpy etc etc... so they're just there by default if you simply install Mu. In this sense, Mu is a sort of "instant Python for education" (just add learners). ;-)
* Bundling - I'm happy for Mu to be bundled if this were useful to another project although I guess this depends upon what use case you're thinking of. For example, Mu is already "bundled" (in a sense) in Raspbian as a recommended package. If in doubt, just reach out.