Yes there will be and we cannot reveal much about it due to NDA. As of now you will be better to read through SQL 2008 CTP4 BOL.
VHD to make it flexible for the user that will install virtual environment rather than having extra one. This is a pre-configured VHD image that requires Virtual Server 2005 R2 installed on your system. Please refer to the Virtual Server 2005 R2 System requirements page here. Any issues for your with this VHD?
Well that is not a constraint I believe when you need to test/develop any new applications on this version. [].
For general public I would say refer to the Books Online for SQL 2008 in this case, as referred we can't reveal few things in thsi regard due to the Non Disclosure Agreement with Microsoft. [].