Application Development

Hello My company is planning to contract the development of a major application. I would appreciate receiving e-mail from software contractors with regards to the following issues concerning custom applications: 1. What is a reasonable warrenty period for the delivered application? 2. If major bugs are encountered after the warrenty period, who typically pays? The contractor or client? 3. What is a good method for "signing off" the completion of the package. What are the major points of agreement and obligations the vendor and the client must agree to? 4. What percentage of the total package cost is a reasonable price to pay for extended warrenty? 5. What other critical points if any should we be examining? 6. Are there any good references on this subject? Thanks Jim Collier Winnipeg, Manitoba Canada