Marvel Studios:how does it work?

While you might think:will this thread work?.....i'm starting it anyhow!
How does Marvel Studios work?....financially,i mean.
When Iron Man came out,i read somewhere,that they had a loan around the area of 700 million.
So....how do they (Marvel) deal with that?.....paying back with (a part of) the profit of movie theaters seems one option,but it might happen with a part of the dvd/blu-ray sales money.
Also,will they eventually make their movies with pure profit of the previous ones?
Someone made a remark about profit of foreign movie theater markets.....he claimed,to have read in a book of an B.O. analist,that 40% of the total profit remained....and later on 17% of that!!! (wich in the case of Avengers,isn't even that bad!)
While Marvel fanboys like me,are really excited about the B.O. results of our favorite movies....we might get help to get in a little deeper! (like merchandise estimates and deals with tv networks after dvd/blu-ray releases....and dvd/blu-ray sales ofcourse!)
Any ideas?