Word has an option you can check/uncheck to determine whether a particular row can break across pages. See under Table Tools>Layout>Properties>Row. As for adjoining rows, you can keep a group together by formatting all of the paragraphs* with the 'keep with next' attribute.

* This will keep each group together with the blank row that follows it. If you don't want that, don't apply the attribute to the last paragraph in each cell on the last row of the group.

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Cheers,
Paul Edstein
[Fmr MS MVP - Word]