Hi. I'm new to xsl:fo and I would like to know if the
widows and orphans feature can be applied to tables (and rows). I
know it can be applied to paragraphs (I tested it already), but I can't get
it to work with tables.

Widows and orphans can only be used to control placement
of lines in a block. They don't apply to whole table rows.
If you want to avoid placing predictably small single table
rows alone on a page, add keep-with-next="always" to the
first row and/or keep-with previous="always" to the last
row of the table.