We are planning, for a future update, to add support for controlling the mixture levers via axis.
For pitch trim you must assign the mechanical commands. https://airfightergr.github.io/les_dc3_docs/commands/#pitch-trim.
If flaps does not operate after take off, most probable cause is that you have exceeded flaps speed limits, and they have failed. Pay attention to the placarded limits on the panel.
DC3 has fat, high lift wings, and if you're taking off without any passengers or cargo, and you are light on fuel, takes off very easily.