Ask HN: How much should I charge for building a website for this startup?

Hello everyone,

I am a student in college. I was recruited by a group of business major friends to build a website for a notes-sharing web-business they are creating. The problem is, I'm not sure what is considered reasonable payment. Currently, the group of creators have been speaking to me as if I'm in their inner circle of founding members. I'm not sure that's the best though.

I'm meeting with the two guys who are in charge (the CEOs I guess, though they don't call themselves that) of the business in 80 minutes to finalize what I'm getting. Something to keep in mind: there's a good chance the company won't take off, but I can see it as very possible for them to rake in several hundred or even thousands of dollars at first. Some things I need to decide are

* Should I ask for a large percentage of first year profits, a smaller percentage of all profits made using my site, or a flat rate?

* How much should I charge?

* Should I consider myself a part of the company, or not?

* Who owns the code, them or me?

I spoke to them briefly about this before and we were kind of hovering around 45% of the income made during the first year. I thought this was reasonable, but I am inexperienced. When I mentioned this to my parents as a side remark on the phone, they instantly became angry and said I was selling too low. According to their view, I should be making 45% of all profits indefinitely while the site I made is being used. They have a lot more business experience than I do, although not with startups and webdev.

What do you think is a reasonable offer? I think it's important to note I have a bargaining advantage because they had a difficult time finding someone who they thought was a competent webdeveloper and they would have a difficult time replacing me