AFAIK, the QtQuick Compiler is a licensed product so you should check with the Qt Company directly. On a side note, it's likely going to be a host tools like qmake or moc so one thing you can try is to copy the one you already have in the binary folder of our self-built Qt.
1:I saw on google that someone else had this error with gcc 4.8. Upgrading solved it. Not saying it will for you. But was the only errors i could find in your log.
2: Sorry I don't know how to solve this. People are compiling for the PI but I never got around to try one
so the details of getting it to work is also unknown to me.
I have a good eye to https://www.ics.com/blog/configuring-qt-creator-raspberry-pi but no board so didnt try yet.