Okay, I'm sorry, armyjudge, but that was nearly impossible for me to read.
riverblindness, I'm going to recap (very condensed) and hope this helps.
1. HR Block has great training for people who are going to be preparing basic personal tax returns. Not necessarily business tax training. Not to say that there aren't good business tax preparers from HR Block, because I know some, but that in general, if you want business tax advice, go to a CPA who specializes is new business startup.
2. No, you do not have to be a partnership in order to write off deductions. Income from the band would be (currently, without making any changes) reported on each member's personal tax return on a "Schedule C" and expenses would be also reported on the same schedule. (This would be the income and expenses that each band member personally received and paid out, so if they got $100 for a gig and split it to $25 each, but Adam paid $20 for gas and Bill paid $10 for parking and Charlie bought dinner for $30 and Dave paid $5 for new guitar picks, then
Adams schedule C would say income: $25, auto expenses: $20, net profit $5
Bill's would be income $25 parking expense $10, net profit $15
Charlie's would say income $25 meals expense $15 (because you can only expense 1/2 of meals, but tell the accountant the full amount, because the form will automatically only count 1/2) net profit $10
Dave's will say income $25 supplies expense $5 net profit $20.)
3. If they want to split things up more evenly, or buy things in the name of the partnership, yes, a partnership is good. There are a couple of issues. The partnership will need to file it's own tax return (1065) which will then issue a K1 to each partner with their percent. So using the above example, the partnership's return will say:
Income $100
Auto Expense $20
Parking Expense $10
Meals Expense $15
Supplies Expense $5
Net Profit $50
And each K1 will say $12.50, which will then go onto the personal tax return on Schedule E, income from partnerships.
If you're going to be doing this anyway, it makes sense to go ahead and from an LLC with 4 members, because you have to do the same things, but you do get some additional legal protection with an LLC that a partnership does not, specifically that the partners are all liable for all expenses of the business (if you get sued then the plaintiff can go after all of the members' personal assets - bank accounts, retirement accounts, house, etc) whereas if you have an LLC and you treat it like a company/business (do not mingle personal and business funds, have a separate bank account for the business etc) then they can only go after business assets. For tax purposes you can choose to have it taxed as a partnership (in which case the partnership files the return, gives you K1s, the income goes on your personal returns as described above) or a c-corporation (the business files and pays it's own taxes, but if you get money out of the corporation you get to pay personal tax on it too) or an s-corporation (you get a K1, but you don't have to pay self employment taxes, which you have to pay on any schedule C or partnership income that's over $400 in a year, but you do have to pay employment taxes and give the partners payroll checks - works to your advantage at about $50,000/year income.).
4. Sales tax is due when you make taxable sales no matter what the entity is - so if selling CDs is taxable in Louisiana, it's going to be taxable whether you're a sole proprietor (just selling it yourself), partnership, llc, corporation or anything else. Sales tax is completely different from income tax and they pretty much have nothing to do with each other. So that would be something to look up (or ask that new business startup specializing CPA).
5. In my professional opinion, it is wise to become an LLC taxed as a partnership. This gives you some legal protection, the taxes aren't going to be much different than they would already, and they can jointly own items, such as the van and other equipment.
If anything was unclear, let me know and I'll try to uncondense.
Eslynne