Basically the way it works is you set up a webserver on you main computer, you point the roku channel you put on that can look at a local webserver (several, but I use roksbox) and it streams the file to the roku. The files must be in a roku complaint format.
Not much to it, but setting up the webserver sometimes throws people for a loop, especially ip addresses and firewalls.
As for the fps for 1080, I am not sure to be honest. I know it can do 30fps, but not sure about 60.