First and foremost, even though it is your house, absolutely consult an engineer to ok everything. Your not talking about a lot of money for them to look it over carefully. My thoughts on the ledger, would be to let it into the wall 1 1/2 inches. This way, it is fully supported, and your not relying on nails to hold up that load. Yes we have all seen decks hanging from a ledger, and yes we have all seen pictures of deck collapses due to improper ledger connections.