Questions about an Internship Offer

First of all, allow me to say hello. I've been lurking around on HN for quite a while now, but now I've got a question on which I can't find any recent discussion, though I feel it may have been touched in the past. Situation: I'm a non-technical. Econ and Spanish Major, Business Minor. I was approached by the founder of a Marketing Consultation startup looking to sign me on as an intern. This would be my first internship and I would be her first intern. And honestly, I don't know how to approach the situation. She has said she wants me to do blogging for her company and work on some of the actual marketing. Furthermore, she's offering to pay, but we did not discuss that much at all (actually, I might have said I'm mainly looking for experience -- was that a mistake?). So far, I've agreed to work with her, and I plan on sending her a sample article to see what she thinks of my writing and to help cement my commitment. Here are my questions: 1. When speaking of pay, what range should I look at? 2. What kind of paperwork do I need to ask from her if she doesn't send me anything? 3. Is there anything I should keep in mind that I haven't mentioned? 4. Any general advice in terms of interships? Thank you for your time!