Keep the questions coming!
We (ANDS staff) will endeavour to answer them as best we can - all answers will be posted here on the bulletin board as well as on the ANDS web site on the DOI Governance Q & A page: http://ands.org.au/cite-data/doi_q_and_a.html
Natasha - In response to your questions about versioning Stuart Hungerford has provided this answer:
A: Yes -- many datasets will change in version, scope and content over
time so it's important to have a strategy for dealing with change. In
most cases the data owner will want to issue a new DOI for the changed
dataset and use the metadata ‘RelatedIdentifier‘ (and other metadata
as needed) to refer to the previous versions of the dataset.
rparker - your question about who mints the DOI:
A:"There are no hard and fast rules for these kind of arrangements--it
may be easiest to have a prior agreement on who mints the DOI just as
the institutions might have for who is lead author on a publication or
submits a publication."
and the one about how can we be sure that only DOI is minted?
A: You can't. To ensure that only one is minted it is best to have agreement
between the collaborating institutions as to which one will be responsible
for minting the DOI.
These answers will also be posted on the above mentioned web page.