#1 (partially) and #2 are covered by FLStudio's very powerful Piano Roll. The feature you want is called (by the makers of FL no less) 'Ghost Notes'.
When you're placing notes on your piano roll, you can toggle the ghost note feature (either from the menu or with ALT+V) and see transparent notes in your piano roll that belong to the other instruments of the same 'pattern' (FL's way of structuring music - you can compose an entire piece in a single pattern or use several). That's #1 for you - it's partially covered because all ghost notes are the same 'transparent gray' tone, so you can't tell which instruments the notes belongs to, but rest assured it displays all notes of all instruments for that pattern (i.e this could mean an entire orchestral palette).
If you use the 'Playback' (scrub) tool, you'll be able to audition all notes in a vertical line (yes, including all ghost ones). So with all instruments playing their piano roll notes as you slide the mouse, that's #2 covered.
The cool thing is, if you double right-click a ghost note, you start editing that instrument's notes (and the notes of the instrument you were previously editing become ghosted).
Look at number 2 and number 15 in this diagram: http://www.image-line.com/support/FLHelp/html/pianoroll.htm
The great thing is that you don't need to ditch your Ableton. You can get the most basic version of FL ("Fruity"), which includes this piano roll, and it can be used in host software like Ableton through ReWire: https://www.ableton.com/en/pages/rewire/fruityloops_studio_6/