No, that's a common misunderstanding. You only need to offer the source code to people to whom you distribute the binary, not any third parties. If I sell someone a box containing GPL'ed software, I need to offer
*them* the source code, not *you*. I don't need to make it freely available. However, if the purchaser asks for the source code, then he can freely pass it on to you if he wants - I can't restrict that right (I can't make him sign any extra agreements, for example).If you have a lot of customers, then the easiest thing is to put your source code up on a web page. But if you have only a few, it may be perfectly reasonable to assume that your GPL'ed code will never "escape".
That's correct, although the GPL'ed Linux ext2 code is by far the advanced implementation around. If it had been under a BSD-style license, for example, then parts of it could give other implementations a starting point.
It's a difficult problem indeed.