1. Possibly, but more importantly the IRS has rules about W-2 vs 1099. If you fall under the W-2 side, attempting to do otherwise can get you in trouble.
2. This is a standard rollover from 401k to IRA. Depending on who's custodian for the money now, some of them make it more or less easy to do the rollover.
2a. I'm not an expert in the checkbook IRA, but also am not sure why you'd want one. Seems like way too much work. Anyway, I don't know why you couldn't have 2 trad IRA accounts. You might want to keep them at separate institutions if accidental comingling is a concern.
3. don't know, sorry. should be a quick google search though
4. Buying an investment is not a business expense. Actual expenses MAY be deductible, but would be the same as if you bought stocks or bonds. (Think fees.) I don't remember the details on this, again google is your friend.
5.
Rent - if you rent an office, yep. If you use your home, that's called a home office and those requirements are well documented.
Bad debt - only if you're accrual basis. Cash basis is easier and more expected for something like what you're thinking.
research items - If you can support why these are needed for research, yes they're deductible. Frankly, your specific examples sound more like you're trying to deduct your personal expenses, so make sure you can convince a dour faced IRS agent with no sense of humor who has the power to bury you in fines and penalties, if not criminal charges.
What you're looking for is called meals and entertainment, and is also covered explicitly by the IRS. Again, you need to make sure that you can convince the dour IRS agent who really thinks you're full of BS.
6. I'm more familiar with accounting firms but they're similar in many respects. In general: payroll, office space/furnishings, utilities, office supplies, professional memberships/licenses, continuing ED costs, subscription costs (legal library, etc), etc. You should be able to figure it out by what your current firm pays for.
However. Unless you're in some really weird area of law, you seem to be playing fast and loose with the concept of what's deductible. You don't get to indulge your hobbies, you don't get to expense your entire wardrobe, and you don't get to call everything a business expense just because you want to. I presume you've been at your current firm for several years at least. You should therefore have a decent idea of what they're paying for. Not because you've seen the books, but because you kinda absorb this stuff. And if you do this, you'll want a decent CPA or similiar to help get everything setup. Also ask them to give you the run down of what can/can not be deducted. Then believe them.
IRS.gov will also be of help. They are the source.