Second, for subtitles I use the simple Title Tool. Font size and type vary, but typically we use 20-24 size. And I have it ride the bottom of the Title Safe area of the screen. The center being about 350 on the Y axis. Mainly because we often go to two lines of sub and the second line at that distance hits the bottom.
Current show I'm onlining has the font size at 20. it all depends on client specs, and the producer's liking