I think Sauron is just enjoying boasting a little, and is to some extent trying to annoy Finrod into doing something stupid, or to cause trouble between him and Orodreth.  Sauron isn't really expecting either of the latter to occur, but he likes showing off and making other people miserable.  Glad you enjoyed it, and thanks for the feedback.

I'm glad you enjoyed it.  There are so many potential stories embedded in the silmarillion it is impossible to think of them all.  I am always running across things I never thought of when I read other people's stories.  Thank you for the feedback.

I can see Finrod and Sauron having very different requirements when it comes to holding prisoners, so Sauron would have run into problems when he took over tol Sirion.  I'm glad you enjoyed it.

I'm glad you liked it. 

I'm glad you found it funny.  I should really move walking into darkness up here.  It contains the answers to your question, although it is a much darker story and entirely too serious.

I'm glad you enjoyed it.  I'm not planning on writing a follow-up letter at the present time but I have some other fix containing Finrod that I should probably move to this site at some point.

I'm glad you enjoyed it.  It was fun to write.