There is wxQt running on top of the Qt5 port, yes, but it isn't that well used. I know someone got Code::Blocks running under it, but they were working on some issues in the wx port still. Development should be like it is under Linux with that.

Qt Creator is indeed in the depots and works pretty well, so you can use that.

If you have more questions, feel free to find us on IRC (Freenode#haiku), the forums, the mailing lists, the bug tracker, or (for ported software) on GitHub (@haikuports/haikuports). Or continue asking here if you prefer :)