I have a few questions about internships in general and I'm sure that these have already been asked but since the employment discussion thread seems to have been emptied out I'm gonna ask them now.

First, are internships generally unpaid? I figure that they are and that if they are paid it's chump change. I'm sure that it depends on the company but I just want to know in general, in your experience.
Second, are internships generally full time or part time? Again, I'm sure it varies but I'd just like to get an average idea.
And lastly (for now) how many pieces should be in a portfolio when applying for an internship? I've looked at Justin Oakford's website (he's currently interning at.... I think Spacetime Studios) and he doesn't have a whole lot, between 15 and 20 pieces if memory serves. Is this generally enough?

Thanks for your time, and if any of you might be needing an intern or someone to clean the toilets around mid April, keep in mind that I will have a portfolio put together soon.