A loan taken out for reasons other than to buy, build, or substantially improve your home, such as to pay off personal debts may qualify as home equity debt. The interest would be deducted on Form 1040, Schedule A, Itemized Deductions. The amount you can deduct as interest on home equity debt is subject to certain limitations. For more information, refer to Publication 936, Home Mortgage Interest Deduction; and Tax Topic 505, Interest Expense.

Most definitely. The addition to your home can also add to the “basis” of your home (the cost of buying the home) to reduce any potential gain when you sell. While increasing your basis is not a huge consideration these days due to the 250,000/500,000 exemption on personal residence – It may be helpful at some point if you live in a market where the home values have soared more than that.

Yes. And the remodeling expense is also a tax deduction, either as a “repair” or an “improvement”.

Yes you can use the equity in your home for many things including a car