I can partially help you here as I am not able to open the .twbx. I only have Tab v10. It appears the viz is crated using latest format.
2) If I display month (using the green column pills) the chart shows Month in full text. I would ideally like to see MMM-YY but cant find this option in formatting.Instead the chart shows one month per year - in this case November
You are right. The MMM-YY option does not come as a a default. You need to Select 'custom' and in the text box write MMM-YY. That should take care.