A quick reply on your "Strange Bugs"

"2. When assigning a parameter for a subreport, SSRS has no dropdown - you have to type the parameter in. When you consider that the parameter name is case-sensitive, this increases the scope for error for no obvious reason."

My experiences have shown that you can get the subreport parameters as a dropdown, but you have only have 1 chance to do so... and that is when you 1st assign the add the subreport:

1 - add a subreport item to your report.

2 - in the item properties assign a subreport (from your dropdown box).

3 - immediately add the 1st parameter which should give you a dropdown list of the subreport parameters to chose from.

4 - go through and add all the subreport parameters and using the dropdown before exiting out of the properties.

* once you exit out of the subreport item properties and re-enter you can no longer add and use the dropdown option.