Regarding the W-9 situation:
About 25 years ago, the commonwealth band I was in had regular gigs at two clubs in Austin, both owned by the same corporation, about 125 dates a year. We had other gigs as well. Our fiddle player took the money at the end of each evening and distributed it to the band in the dressing room, a very common scenario.
He filed an honest tax return based on his yearly music income of +/- $15K, but got kicked out by the IRS computer. "Mr. Swanson, you claim income of 15 thousand, but our records show Silver Dollar, Inc. paid you over $60,000 alone." Yes, he was audited

, and each of us in the band had to submit letters to the IRS verifying that, in fact, Mr. Swanson DID distribute the monies to us individually at the end of each engagement. I'm sure this information was compared against all of our individual 1040 returns. Fortunately, no one else in the band was audited, but Rusty's returns got reviewed for the following 3 years.
My advice: BE HONEST WITH THE IRS! I declare ALL monies I make as a musician; checks, PayPal, AND cash... even if part of the cash is quarters taken out of the pool table and later spent on a coffee and donut for the drive home. Take advantage of ALL legitimate deductions, some of which are actually pretty generous, like the mileage and per diem amounts.
I have an excellent CPA, who knows how each expense I claim on my Sch. C is related to my business activities and can discuss the information specifically with the IRS if needed. My income, it should be noted, isn't only cash from playing gigs, but also income from writing, producing, and selling instructional material, so my Schedule C, and therefore my legitimate deductions, might be more extensive than that of just a weekend honky-tonk player's.
To me, it's MUCH easier to just claim all the money and take all the deductions than it is to lie, commit a crime, and then worry each year you might be found out. And if you owe money, cowboy-up and pay the damn tax.
To me, my sleep is more important than whatever few bucks I'd be dubiously "saving."
My rig: Infinity and Telonics.
Son, we live in a world with walls, and those walls have to be guarded by men with steel guitars. Who's gonna do it? You? You, Lt. Weinberg?