Wednesday 14 April is indeed the date. Tickets go on sale in January 2010.
The concert will feature the New York cast of principles. So, yes to Helen Sjöholm, Russell Watson, Kevin Odekirk and Louise Pitre.
Gary Collins tells me that The Official ABBA Fan Club will also have the CD of the New York concert recording on sale at the Roosendaal event on Saturday 10 April 2010.