I know this is a VERY old thread, but I just ran into this myself. Never tried using Trook with Calibre for some reason. What I found is you have to add /stanza to the URL
http://fullIPofyourcomputeronyourhom...calibre/stanza
for example:
http://192.168.2.502:9391/stanza
The server port is what you set up in Calibre. Check your router for your computer IP or get it from the network config on your system. You don't need a name and password unless you forward the port to your computer in your router's setup. If you do that, the your Calibre server is accessable from the internet and YES it should have a password. Personally I never thought it was worth the risk. I also don't have the server running by default as I don't need to download books from it to my devices very often.
Also, you CAN download books from Calibre via the NookDevs browser. It is not near as nice (or fast) as Trook but it works. Just use the same URL but without the /stanza