North East is an ocean to explore, one cannot bind it in a time frame. It's a moment to live in. It's been around 6 months since I visited Tawang and I am really not finding that satisfaction anywhere. Well I have just one suggestion for u before starting the itenary-"leave everything and visit Tawang"
If you have made your mind than you are the luckiest person travelling in India...congratulations. Be ready to travel in Sumo, eat local fruits and much more.