Since it looks like you're using Tableau 10.5 you could take advantage of the viz within a tooltip to achieve both of your questions. Check out this article for how to retrieve top N names by year
Then you could just add that "Top 10" sheet into your tooltip and filter on year
<Sheet name="Top 10" maxwidth="300" maxheight="300" filter="<YEAR(Year of Birth)>">
Thanks so much for the response - I've tried to filter for the top 10 using the INDEX option in linked article, but the output was this:
(I had a similar result when I swapped the items in Columns and Rows to be more consistent with the example in the article.)
I've tried the RANK option, but I get an error when I try to enter the calculated field, since Tableau requires aggregated values when more than one data source is used (my data come from a txt file and an Excel file). This may still be an option if I can find some shortcuts that would make it more feasible to merge the two documents into one source.