Need some Advice

I've just begun with the whole Freelance writer thing and have a few questions of folks who steps I'm following in.

1. How much do you have to make before you have to claim on taxes? I've heard way too many rumors to just guess.

2. Should I create a small business or can I do this as an individual and my ssn?

3. What are some of the best places to find writing work? I already belong to IFreelance.com but was wondering if there are any other good sites out there (other than craigslist).

Any help or advice would be greatly appreciated.

Thanks,