Quote: "1) is it free to use personally, or do you need a licence?"
$99 dollars USD per year to join the developers club and for the license.
Quote: "2) Is it hard to learn?"
It uses C#. Shouldn't be difficult to learn at all.
Quote: "3) How is it complied? Do you compile it on windows then transfer to the xbox harddrive, or transfer to xbox harddrive and compile, or can the whole thing be done on windows? (including testing? )"
It has to be tested on an XBox, and you need your XBox to be connected to the internet to do so. That's all I know.