P.S. About 5. %QTDIR%\src\gui\accessible\qaccessible_win.cpp compilation problem.
I try to comment second interface at line 267:
class QWindowsAccessible : public IAccessible, /*IOleWindow,*/ QAccessible
Compilation was successful. After that I found this error in gcc bug database.
Take a look to description GCC Bugzilla Bug 27067 "Compile errors with multiple
inheritance where the stdcall attribute is applied to virtual functions"
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27067

I try to compile Qt 4.2.2 with snapshots gcc-4.1-20061219 and gcc-4.2-20070102,
both compilation was unsuccessful. Same errors "'x' aliased to undefined symbol".
Patch was not included in source tree.