descending = highest to lowest
ascending = lowest to highest
"Text Search Relevance" just means that the search is only sorted by relevance to the search text.
Other sorting methods will still show results relevant to the text search higher.
This currency conversion is only an estimate.
Conversion rates are only updated once per day,
and will probably not reflect the exact rate
used to charge you if you were to purchase.
(although it will probably be close)