VS2012 (I advise updating to Update 4 version which is up to date at the time of writing this) provides a number of updates regarding SharePoint 2010 development. Some of them are:
- Create lists and Content Types by using new designers
- Create Site Columns
- Create Silverlight webparts
- Publish SharePoint solutions to remote SharePoint server
- Test SharePoint Performance by using profiling tools
- Create Sandboxed Visual webparts
- Improved support for Sandboxed solutions
- Streamlined SharePoint Project Templates
- Test you code by using Microsoft Fakes Framework
Any version higher or equal to Professional will support SharePoint development. Please refer to msdn on what other functions are included in the premium edition. Other than some code quality tools, the professional version should be sufficient for your development needs.
As for the last question, I do not see why you would cease to use SharePoint lists and work with SQL Server directly...? I do not see this as a best practice and you will probably rarely find yourself ever needing to work on the databases themselves. Everything you need most likely is contained within the SharePoint Server Object Model.