if you write the code, it belongs to you. you can choose licensing on what you have written.

would depend...
several colleges and firms have a clause in their contracts that states that, if you write it using their hardware (a pc in a lab at college, a laptop from work, ...) the code (and the rights to it) is theirs

if you write it on your own pc in your own time, it's "yours" assuming you're not using some pattented idea or concept (don't really know the full implications those can have, but they differ from country to country)

ah yes, forgot about that, definitely needs to be considered...

thank's sillyboy, it's a question that's been driving me nuts.