ASP.NET Session Problem

Question

Hi..

1st Query......
I have a session variable cityId through which i find all the record. When i leave my application unattended  for  sometime then session expires & it does get the value for city & then throws exception.  How I can redirect to a error page when session expires like this.

2nd Query

When I click some page(myprofile.aspx), then i checks if the user is loged in or not, if user is not loged in then redirect to the login page & if loged in then show the page
If I give the user login if user not logined to view the myprofile.aspx then when the use logs in the it should directly go the myprofile.aspx page rather than whatever i provided after login.

Help Me Out.