To open in a new window I use this
&ParameterName=" & Parameters!ParameterNameDepartment.Value & "
It should be all one line but I CRLF'd it to make it more readable. For the url I usually open the report I want to jump to and just copy & paste the URL. I added a papameter too so you can see how that part works. yOU can name the wondow too by replaceing the Window Target Name Value.
This syntax is very picky, a lot of times I have to cut my losses and start over with one that workss and slowly replace stuff until it works.