Good for you. But, that doesn't mean the added square footage is the factor. No, its what they value your property at, irregardless square footage. That is, the improvement adding to your property value, irregardless the square footage added, is the factor. Contesting their assessment is always a good idea if it increases as a result of some improvement.
You forgot views. A view of the surrounding area from your property is also taxable. No, I'm not kidding.
School district?
I refuse, and continue to refuse to use any "online" form of banking. I do continue to use a personal computer without internet access to keep track of my banking/investments.