- I would advise you to focus on classes and object oriented programming. You will be able to catch up with the C++ imperative part if you already know any other imperative programming language. Keep in mind that you rarely ever need to deal with manual memory management. The STL (or Qt's) does it for you.

For a book about C++, I'll would go with C++ Primer.

- Qt by itself is a little bit weird, because it introduces its custom build process and it mainly uses a signal/slot mechanism for communication (thinks callback). Have also a look at Qt Quick, you can design an GUI without writing a single line of C++. There is a list of books about Qt there : https://wiki.qt.io/Books