glad to hear ALK has sparked your interest. We are working hard on releasing the Windows version at the moment, therefore feature updates are on hold and we are releasing only critical bug fixes for ALK. There is a number of features that our users have requested, the top priorities being setlists, first loop sets tempo functionality, side chaining and Ableton Link (+ MIDI Clock sync). We expect to release the Windows version towards the end of the calendar year and afterwards we will start work on the new features. To answer your questions:
Yes it can be done using Command tracks.
No, MIDI Clock sync is one of the desired features that will see the light some time next year. Honoring input MIDI Clock transport signals should be easier and might be implemented sooner.
Unfortunately, ALK does not have sidechaining capabilities yet - the only possible input for an audio track is an audio source (while the only input for Instrument and MIDI tracks is MIDI). It will be implemented after the Windows release (the underlying code infrastructure is roughly there).
There's no counter capability yet - the user has to send a MIDI command to get out of the loop. However, I think that adds a lot more flexibility than having to resort to a countdown, especially coupled with the option that the jump outside of the loop can be deferred to quantized values - after the user sends the MIDI command, it can be triggered Immediately/next whole note/next half note, etc. or at the end of region.
There is a silence MIDI button which does not have a key shortcut and cannot be triggered by MIDI at the moment. Making it assignable to a command track would be a small update and could be done quickly. Please note that the button, along with silencing all notes and all channels also stops transport and is meant as the last safeguard against stuck notes. We've put in a lot of effort to stop notes being stuck due to looping/changing to monitoring/exiting region, etc. so the button's purpose is to address VSTs misbehaving and other unexpected behavior...
I hope that answers your questions and that you will soon have the opportunity to try out ALK yourself!