By closing before January 1 you will be able to claim a Homestead Exemption on the property taxes. You must file this exemption before May 1. In Dallas County this should result in a 20-25% reduction in your total property tax obligation. Check http://www.Dallascad.org or http://www.openingtilclose.blogspot.com for more infomation.
Regarding interest and closing cost deductions:
At the end of the year, your mortgage lender will mail you Form 1098 which itemizes the amount of interest paid for the year. This is the amunt to claim on Schedule A if you choose to itemize your deductions. Even if you made some payments in 2008, the amount of interest paid might not be greater than your Standard Deduction. If you use he Standard Deduction, mortgage interest paid is irrelevant since you are not itemizing.
Closing costs may also be deducted if the closing costs are itemized on your Settlement Statement. Only one time charges are eligible for deduction such as lender fees, discount points, appraisal expense, etc. Recuriing charges such as money placed in an escrow account for property taxes and insurane are not deductible.
If you choose to deduct closing costs, they must be amortized over the scheduled term of the loan. For example, if you have $3,000 in eligible closing cost deductions on a 30 year loan, each year you may deduct $3000 / 30 years = $100 deduction on Schedule A. Closing costs may opnly be deducted if you itemize on Schedule A rather than using the Standard Deduction.
If you sell the home or pay off the mortgage through refinancing, you may deduct the remaining unamortized eligible closing costs.
I think you should be able to claim taxes and interest from Dec 8th through the end of the year.
I would agree with the other agents about getting a CPA, this way you will be sure.
Also, just as a reminder, be sure to file your Homestead Form.