Visual Studio 2010 is only required to develop the workflows for Project Server 2010. Also VS2010 requires to be installed on the server, yes you cannot access the server remotely for development, to develop project workflows.
Other versions of Visual Studio could also work to use WCF services for integration or customization purposes.
| Khurram Jamshed | Follow my blog about Enterprise Project Management Solution | http://khurramjamshed.blogspot.com |