Designer thinking about going freelance, input needed

I'm not sure is this is going in the proper sub forum or not, but I figured this site has a wealth of freelancers on it so where better to start. Any input is greatly appreciated.

Ok, let me start by saying I've been in the t-shirt design field for approximately 7 years and recently finished some schooling. I am currently employed full time in a print shop heading up the screen printing department, so I'm not completely new to this realm. I've decided to offer design services part time (right now anyway), but when it comes to business I don't know the first thing. I've read several good blogs on this topic that have got my gears in motion, but I'm still unsure about a lot of things. Obviously, a portfolio site is needed along with some branding materials like business cards. After this point, I begin treading in uncertain waters.

What kind of invoicing software should I use?
Should I buy a domain or just use a site like deviantart or carbonmade?
How much should I charge?
How do I get paid?
How do I find clients?
Should I find an accountant?
Do I need my business license?
Do I need insurance for my business?

Any insight you guys could offer up would be extremely helpful. Thanks in advance!