A. Yes. The IRS has ruled that Land Installment Contract's qualify for the First Time Home Buyer Tax Credit - see http://www.irs.gov/newsroom/article/0,,id=206291,00.html (10th item from the top).
You are entitled to receive a tax credit of 10% of the purchase price under the Land Installment Contract - so in the above example, the IRS will issue you a check for $8,000.00. The maximum credit is 10% of the purchase price, up to an $80,000.00 purchase. If the house is $90,000.00, your check will be still be $8,000.00.
Specifically, you will file an amendment to your 2008 tax return, using IRS form 1040X (we help you with this). Assuming you have already paid your 2008 taxes, you will receive a CHECK for $8,000.00.