With a wide experience using Python together with its graphical environments (Tkinter and wxPython), and having embedded CEF, that we know quite well at the source level, on several browsing applications, including Javascript control, cookie handling and all kinds of hooks provided by this framework, we can manage any features supported by it in a solid and well optimized way. From the modifications you propose, the only problematic point is the one related to memory consumption, which originates on the internals of the Chromium framework itself and, due to the structure of cefpython, increases considerably with each new browser window. There is few to do about that at the application level except trying to limit resorce usage. For all the remaining features there should be no problem to implement them as described.
Regards
The Bramfeld Team