1a) I'm not sure I understand the question - I've probably missed something
1b) From our point of view the second system may be run by someone else e.g. the Central Computing Service, but the Course Support software (dotLRN) will probably be run by us as we offer close pedagogical support as well as IT support.
2) I'm not technical enough to answer, but my mention of XML was to illustrate how I think about the problem not necessarily to suggest it is a necessary or sufficient solution
3) I don't think there is anything established yet (or likely to be in the near future) so something flexible will be essential
