What are the conditions and rules for someone to declare his or her assets as Waqf? Besides, does it apply for intellectual properties?
If you can understand Arabic there is a scholar whose name is Abdullah bin Bayyah. He made a lot of research in this topic. He also has an english version of his site but I don't think all of his researches are translated to english unfortunately.
I'm not a scholar but I'm interested a lot in this topic.
For your second question, from bayyah's research, I remember that intellectual properties were considered as waqf because it produces money as the publisher can buy and sell these intellectual properties of books.