Get the code using Tortoise HG, using those download links on codeplex does not produce a good result.
See The .NET 4 Transition Plan, use .NET 4 if at all possible ie use a .NET 4 application pool if using IIS.
See items 9 and 10 on the FAQ
You can always safely visit the /Setup/Default.aspx page but if you are using the same database then it will not run any scripts since they already ran.
See my answer about skin files on your duplicated question on this thread.