Other boards like the economy, general discussion, gambling, altcoin etc is well spelt out and one can easily know why it is necessary to participate and identify in these boards discussions but my question is with regard to the local board.
Local boards are there to help the local languages, it's not because other languages are considered to be local but because there are certain group of people from other part of the world that don't speak English language and the forum by default is English format, so there is need for these other languages that speak their native as official language to help understand what is happening in the Forum.
1. Is it necessary for everyone to identify with their local boards and participate in the board discussions?
Not necessary but if you know how to speak English language and know much about bitcoin but your local language don't understand some aspect of bitcoin, wouldn't that be concerning to ignore them when you can just help them out. It's not compulsory but your presence will help grow the local board.
2. I would love to get a detailed aim For each of the local board and also know the kind of thread that's best to be created in the local board.
Local board are just sub board of what is happening at the upper level of the forum, some have it's sub board while some don't, they use general thread for discussion, it's just like using the main forum but in your local language.
3. If it's necessary to participate in the activity of the local board, what happens to the people whose local board is not in the forum.
Not necessary but as I said earlier, it will help grow your local in the Forum and if your board is not available, there are
other languages/location where you can create unofficial thread for your local language to communicate with eachother and discuss bitcoin and other related stuff.