Authentication And Authorization Options?

I have the usual requirement of implementing Authentication and Authorization. I used to implement it using custom code where I have Users, Roles, Role_Pages, User_Pages, and User_Roles. So this way we can give a certain user roles (that group multiple pages) and/or directly define access to certain pages. All that with the ability to specify fine grained permissions like the ability to Add/Edit/Delete records in those pages.

My question: How easy is it to implement this using Forms Authentication and what advantage does that give over implementing a custom solution. I am also concerned with knowing if there would be any advantage when it comes to securing from session hijacking and against spoofing where an attacker could replay requests and impersonate legit users. Would Forms Authentication have any advantage there, or is it only SSL that can secure against that (which makes both approaches equal in that regard).