Changes to ASP.net C# website

We have a document management site written in C# and need some updates/fixes for the site. The updates are below. 1. Fix error message when auto logged out. When a user is automatically logged out (expires) and they try to access a restricted page they get a server error message. I would like it to simply redirect them to the login screen instead. The server error is usually: "Cannot perform runtime binding on a null reference" because the page is trying to get their userid but this doesn't exisit since they are not logged in. 2. Add a new user to loan access. Our documents are split up by loans. Each loan currently has two methods of assigning user access, Deal Team (for admin access) and Assign Access (for front end user access). We would like to split the Deal Team into two separate pieces: Deal Team and Admin Access. The Deal Team is a list of people that appear for the front end user when they need help with a loan, only admins can be in the Deal Team. Currently the Deal Team list is used to assign which admins have access to the loan. We want to separate that so there are two lists, one for Admin Access and one for Deal Team. 3. In the same section where users are assigned access we want to add a button called "Mail List". When a user (Admin, Deal Team or front end user) is assigned to the loan we want to add a check box for "Mail List." This should update the database to a new field which will send out emails only to people assigned. Right now we do not need to worry about sending the emails. We only want to setup the feature which allows us to assign people correctly. 4. We have some button called "Move PDF" these work well, but when a document is rejected, approved or marked as required the buttons disappear. We need to make sure the 'Move PDF' buttons always appear when they are supposed to. Thanks and please let me know if there are any questions.