1)Is it possible to change the way it displays consecutive references in-text, 1-3 instead of [1,2,3]?
No. Microsoft Word 2007 passes only one Source (with a few extra parameters) at a time to the stylesheet when formatting citations. So each part of the in-text citation has no knowledge regarding its siblings and therefore it is not possible
to built in logic such as sorting or grouping of numbers. Also, while trying to find a workaround, I learned that Word expects a return value from the stylesheet for every citation in the group. If it does not get any (because you are not outputting anything
for the second citation), it will add "Invalid source specified." to the text.
Personally, I think Microsoft made a mistake here. It would have been a lot better if they had passed all sources in a grouped citation in one go, in the same way bibliography data is passed around now. That way, stylesheet developers could have added their
own logic such as:
- leaving out certain citations in the group
- sorting citations within the group
2)Also, can we change the in-text style, from  to supercript 1, for example?
Superscript is not possible. It seems the in-text citation automatically copies the 'paragraph style' of the paragraph to which it is added. This does not hold for the full bibliography which uses a separate paragraph style called MsoBibliography.
Formatting such as bold, underline and italic can be applied though. So it seems as Word 2007 does some 'sanatizing' of the HTML you pass for in-text citations.
remark: this is a replacement of an earlier post which provided a flawed solution (empty citations)