It gets complicated, and naturally, it’s the IRS that gets into your stuff if they don’t like what you’re doing, so the “law” can have varying application (because they can give you hell without ever taking you to court.)
Basically, the best definition of the difference between a employment and contract work (which I believe is what you’re asking about) is a combination of who pays you, what your benefits are, and whether you work solely for one party. If you work for one party and they strictly define what you do every day and your hours, the IRS will typically consider you an employee. If your situation varies from that, you may be able to call yourself a contractor without trouble.
My work is kinda interesting in that regard. For most of the last 15 years or so, I’ve “worked for” a company that rents me out to exactly one other company (at a time–it’s been three or four.) I “get away” with that because the company I “work for” does the payroll taxes, benefits, etc., even though my work product goes to “the client.” The whole REASON for the middle man is because of the IRS.
Because of the arrangement, I could decide not to show up for work when I choose, decide not to do things exactly the client’s way, etc. Of course, those would be bad business decisions, and could lead to my client deciding they no longer have work for me.
The IRS MAY come after ANYONE for taxes. It’s all based on having income, if they know.
Minors can work if their state lets them. The easiest way is to work under the table, but if they know, there are forms to fill out, etc. As a teen going to a private school, I had to get permission from a public school bureaucrat to work at a restaurant before being 18. The “job” I had gardening before that was under the table, and required no such nonsense.
If you work under the table and the IRS catches you, they may track you down and bill you for back taxes. It happened to me in my first job writing software, when my employer was audited. He gave me a surprise 1099, and the IRS additionally billed me for previous years. A 1099 form is a statement that a business has paid a contract worker (among other things) without deducting any payroll taxes. It essentially rats you out so you nave to pay taxes.
Maybe it would be best for you to ask someone like Melanie about the feasibility of any particular plans.