This slipped by initially, but this is not true, there are penalties for withdrawing from a Roth IRA before age 59 and a half, outside of for specific purchases, also, if your Roth has not been established for at least 5 years, you do not get the tax benefits from it.
0% loans generally are not for cars, they are for things like computers or furniture, expensive items, but not at the level of a car or a house. Companies do it to increase sales because a lump sum payment of over $1000 often pushes away some potential customers. (They also write the agreements to be very punitive if you miss a payment) Maybe you can find some instances where you benefit from a lower cost paying in full immediately, but the general rule is that the cost is the same regardless.
On car loans, this is more inaccurate. Most dealerships want to push you to financing because they actually sell their own financing products now. They benefit from it. Getting them to make you a deal, if they know you are paying cash, is more difficult. That doesn't mean you shouldn't pay cash if you can, but you should negotiate price letting them assume you will be using their financial services, and only when you get an out the door price that you are happy with let them know either that you are paying cash, or have arranged financing separately through a bank.
I opened a side business LLC as a sleeping consultant so I bill myself for my sleeping time as reasearch, pay myself, AND all my sleep is a business expense I can write off. 
