Q. Are there any limitations or performance impact on breaking permissions inheritance in a list?
A. Yes. In addition to making it difficult to manage permissions, breaking inheritance for every granular object like list items can cause a significant impact in performance while accessing the list. Also there are limitations imposed by SharePoint 2010 on breaking permissions inheritance. Refer to the “List and Library limits” at http://technet.microsoft.com/en-us/library/cc262787.aspx#ListLibrary.
Q. Can we disable specific permissions that can be granted to users by the site collection administrator?
A. Yes. It is possible to disable the granting of certain types of permissions to users by the site collection administrator. This is done by ...