Should probably point out that's it's just a table, not a person.

Across the library tower from Dorian. Facing out from your throne: Second door on the left, up the stairs, take a left, on the left side of the tower on that floor. 

For the life of me I can't remember her name. She's a tranquil that is in the library area, where Dorian hangs out. Hover around the different tables and you should find the research one. It took me forever to figure that out too.

yup. just fast travel to leliana and go down 1 flight of stairs

I have searched high and low in the castle and on the map and for the life of me must have missed it :/

Possibly dumb question- In Skyhold, who is the new person I hand in my enemy drops to to analyze them and give me a dmg bonus against them?