Ability to experiment/play MIDI keyboard before writing it out

I wish MuseScore let me experiment with a MIDI keyboard before writing anything down. Experimenting on a piano before writing it down is a common workflow for composition, but current MuseScore behavior prevents this (see the three behaviors listed below).

Expected behavior 1: Keyboard plays the instrument sound of the currently selected staff
Actual behavior 1: Keyboard plays the instrument sound of the top staff, regardless of what you are working on.

Expected behavior 2: Note length should match what ever I play on the MIDI keyboard
Actual behavior 2: Note length is always 300ms (or whatever is defined as the standard length in Preferences > Note Input). To clarify the standard note length makes sense during note input, but doesn't make sense when you are trying to experiment before committing to writing. I can also see the potential need to have a maximum note length to avoid MIDI notes that get stuck (the note off message got lost, etc.)

Expected behavior 3: Note playback should be more or less instant
Actual behavior 3: Usually there is a significant delay between hitting a note and hearing it. Maybe MuseScore already has options to reduce this. Again a small delay is not significant during note entry but is significant when trying to experiment with a melody or rhythm.

As a work around, I often composing with pencil and paper at a piano then come to MuseScore to write it out nicely. But when I'm in a hurry, it would be nice to skip the two step process.