I recently hired my brother-in-law to help me do some work for a week. Should I file him as a contractor on my 1099, or would he be filed as a regular worker on 941?

If he only worked for you for a week, and you paid him in cash then he would be a 1099 contractor. However if you kept him on, and put him on the payroll he would become a 941 regular employee.

What are legitimate vehicle and travel expenses I can claim as deductions?

The IRS defines legitimate deductions as those that relate directly to your business. Seems simple right, but how does the IRS determine what, "relates directly to your business" mean? Let me clarify by showing some examples...If you're on the road a lot and you have to perform regular maintenance on your vehicle and regularly change out the tires; that would be a deduction. If you have your work vehicle detailed to advertise your business; that would also be a deduction. Any changes to your vehicle that don't relate to business; like putting in a new sound system or any other "luxury" installations would not count as deductions.

I sometimes do work under the table. Will I get in trouble for that?

If the IRS finds out about it yes, you will get in trouble. You have to report any income, even if it's for "bartered" services, or giving a friend a discount while you're not "on the clock". The IRS can bust you for not correctly reporting your income.

What will happen to me if I can't pay one of my quarterly payroll taxes on time?

You should always pay your quarterly payroll taxes on time, even if it means your business has to suffer a little. If you don't file on time interest and penalties start to add on to the amount you owe immediately. If you put it off until the next quarterly payment is due, you will have a significant debt on your hands that can quickly snowball.

Can the IRS seize my work vehicle and all of my work equipment?

The IRS isn't completely cruel. They want you to be able to work; after all they do want their money. You can keep any tools and a vehicle that is necessary for your work. You do have to prove to the IRS collectors that those assets are required to perform your job.

Now you have the smoking gun...Use it!