Here's some explanations:
1.Static transformations = ?!! vs Just in time transformations
A static transformation is the act of running an XSLT transformation once and deploying the resulting XML document to use. A just-in-time transformation, on the other hand, would be to perform the XSLT transformation every time someone needs the resulting XML document. The benefit of static transformation is obviously performance, because you're only doing the rather expensive XSLT transformation once. One reason to use just-in-time translation could be that the input is changing so frequently that a static transformation is not enough -- i.e. you can't do the transformation and deployment all the time so you have to let it happen at runtime.
5.Mixed content model = ?!
If an element has mixed content model, it means that the element can contain other child elements as well as plain text content. For example:
6.Just in time generation of XML documents = ?!!
See my answer to 1.