I am new to investing (focused just on flipping right now)and have never run a small business. Through books I've read recommended on Bigger Pockets and researching, I know that you need to have independent contractors fill out a W-9 and then send them a 1099 at the end of the year.  I have a couple of questions that for some reason my accountant can't seem to clarify for me.

1.) How do you know which contractors you use need to fill out a W-9? For instance, I know that a couple of my general contractors have their own LLC and are smaller companies and therefore probably need to fill them out. If I use a large company for HVAC or something, I imagine they don't need to fill out a W-9. I was wondering if there is a definitive way to know who to have fill out a W-9 so I don't just throw them at everyone like my accountant suggests.

2.) If I am using a general contractor to manage my whole project and the cost of the subcontractors that he uses are rolled into his lump sum fee that I pay over scheduled increments, do I just have the general contractor fill out a W-9 since I am only issuing checks to him?

3.) When filling out Independent Contractor Agreements, do I literally have each subcontractor fill one out?  And again, if my GC is managing everything, do I need to have all of his subs sign an Independent Contractor Agreement or is it covered under the one the GC signs since I am just paying him?

Sorry for questions that I feel are probably very basic, but I've been unsuccessful in searching the forums, searching online, and in talks with my accountant.

Thanks!