This circumstance is only valid for travelers milking visa exempt entry stamps, in all likelihood if you already possess a valid multiple entry visa and are simply border bouncing to activate another entry then you most likely will not need to stay overnight.
Most of what you're asking is Embassy specific, 3 months is generally enough, if you can show you have a portfolio and client list and appear genuine. A lot of it is having a brief convincing cover letter. As far as bank statements there are 2 different types, the 500k funding, and the freelance income payslips/deposits/ whatever related to your contracts/gigs. On top of that a tax return might be requested, in your case of only being viable 3 months it's moot. Again, it's up to you to provide a convincing application with a brief cover letter explaining how your situation and documents either tick off the boxs, or the reason why it doesn't.