I need to understand the best practice for developing SharePoint solutions for sites that exist already on the production server. I am currently trying to create a visual webpart for a list that exists on the production server. What is the best method for me to debug my web part locally on my development box that references the production list.
In general, you should avoid directly connecting to PRODUCTION for any sort of development or debugging. Consider bringing the list to your development environment. You can use import/export or consider saving list as template and install the template in Dev environment.
How should you develop, debug and deploy sharepoint solutions?
The serious development projects typically follow SharePoint Application life cycle described at: http://msdn.microsoft.com/en-us/library/gg604045(v=office.14).aspx
The process can be modified slightly based on your need.
You can create a quick and dirty copy of the list from the production server by creating a list template from the list settings screen. When you create the list template, you will be given the option to include the content as well. Make sure that is checked.
Download the file from the list template gallery in production, then upload the file to the list template gallery in your Dev environment. Create a new app in Dev and you should see your list template as an option. Creating this list from that template will create the list with the same fields and data as the production site.
A nicety that comes with this is that if you screw up your list in Dev, you can just delete it and create a new copy from the list template and get a fresh copy of your data.