How do I modify my profile information/change my password, etc?

The profile settings are tucked away in the menu, under Questions > Profile Update.

There you will be able to change your password, First & Last Name, email address, phone number, address, Twitter ID, and Skype ID.

Once on this page, you'll have access to other tabs as well that will allow you to view your payment history, active subscriptions, and renew/upgrade your current subscription.