Im building a new deck and will say this is my first time. The decks ledger will be the same size as the one I removed (see pic). My question is why would the house band seen in the picture be in two pieces? As that the ledger conection is a very important acpect of the structural integrety I want to make sure the is normal before I go ahead.
That is odd to see the house's rim joist broken over the door or window opening below. What often happens is there are two rim joists, and they splice one. Sloppy, but in all honesty if it hasn't been an issue yet it probably won't become an issue (since I'm a building inspector, I'm saying that with my fingers crossed behind my back ). It should probably be fixed, but fixing it would probably be a very invasive and would probably require an experienced carpenter.
When you bolt your deck's ledger to it, it will serve to strengthen the splice as well. You might plan your bolt pattern to aid in accomplishing that.
Be sure that you install some flashing over the existing framing overlapping the siding to make sure that water doesn't sneak in there and really mess things up. Some 15# felt would be a good idea behind the flashing up against the wood.
Good project for a newbie carpenter. Give us a holler if you need anything!