You will probably have to pay royalties and these vary dramatically. The Copyright for Higher Education Research Guide gives more info on getting permission.
Make sure you are getting permission from the person who has the authority to give it.
Most lawsuits originate with disgruntled employees.
WATCH List:: Writers Artists and Their Copyright Holders is a database of copyright contacts for writers, artists, and prominent figures in other creative fields from the Harry Ransom Humanities Research Center – Univ. Texas Austin.
FOB: Firms Out of Business is a database with information about vanished publishing concerns, literary agencies, and similar firms.
WATCH and FOB are run jointly by the Harry Ransom Center and University of Reading Library.
The Copyright Clearinghouse can help you identify the copyright status of a work and take care of the royalties for you.
Many others are listed on my Copyrights ad Responsibilities Web page under Research