… Calc could be used by changing the background color of the whole row where a specific column’s cells match strings…
Why not? If you want to set a style or a BckColour known in advance, you may use the STYLE() function under a condition for cells containing a formula or(/and) conditional formatting in general.
… For example: a cell in column B contains string foo bar
and every {?} matching row’s background should be colored the same…
There is no Calc function (afaik) to return the cell style name (or in specific information about the background colour) of a cell. Therefore you canot use the STYLE() function or conditional formatting setting the same … for other cells. You will have to go into programming for this purpose - and you will have to read about accessing cell properties (and additionally style properties?). All the disadvantages of using macros for free!
How comes Notepad++ into the game?
Editing (with regard to comments from 2014-12-21 by @rautamiekka )
I already suggested to use conditional formatting for the task. How I would do it in detail you can find in the attached example: ask43887HighlightMatchingRows001.ods
[PS In the few cases I had to use Notepad++ on an ods, I had first to close it and extract the content.xml.]