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To answer your question about self employment tax. If you had a tax liability for 2008, you may have to pay estimated tax for 2009.
You must pay estimated tax for 2009 if both of the following apply.
You expect to owe at least $1000 in tax for 2009 after subtracting your withholding and credits.
You expect your withholding and credits to be less than the smaller of;
90% of the tax to be shown on your 2009 tax return, or
100% of the tax shown on your 2008 tax return. Your 2008 tax return must cover all 12 months.
Sole proprietors, partners, and S corporation shareholders generally have to make estimated tax payments if you expect to owe tax of $1,000 or more when you file your return.
Use Form 1040-ES, Estimated Tax for Individuals, to figure and pay your estimated tax. For additional information, refer to Publication 505, Tax Withholding and Estimated Tax.
You will find information about when and how to file by going to this IRS article.