Again, thank you so much for looking into this for me. I had planned for ten working days but didn't realize that there were so many Indian holidays.
I am planning on taking the night train from Chiang Mai to Bangkok Thursday night, if it is still possible to get my passport back on the 10th. If it's not going to be possible, then I would leave later and I need to reschedule my flight to Delhi and I will have to pay for an overstay of 3 or 4 days :-(