Home Office Expense Deduction - Actual Method

I plan to use the actual method (rather than simplified) to calculate home office expenses. As this is my first year operating a home-based business, I would like to clarify a few things before submitting my tax return docs:

1. Is there a way to see TurboTax's exact calculations for home office expenses? I followed the instructions for the actual method using Form 8829, but my calculation differs from what TurboTax shows, so I'd like to compare both calculations to ensure accuracy.
2. I received two Form 1098s as my mortgage was transferred to another servicer during the year. I have entered both forms into TurboTax. For purposes of calculating home office expenses, does it matter which mortgage I assign points paid at origination?
3. For purposes of calculating home office depreciation, what is the recommended way to enter the value of my home into TurboTax? Would there be any drawback to applying the total purchase price to Cost of Home and $0 to Cost of Land?