This thread should help you on your first question (the same information is documented in the Tableau Server administration guide, which you can download):
When you pass in parameter / filter values on the URL, they are automatically applied to the report - is this what you mean by "hwo to consume these URL parameters"? You don't need to do anything special.
Hope this helps!
Thanks. I still need to try this.
I'm using this undocumented feature e.g. http://public.tableausoftware.com/views/RegionDashboardMini/Trends.png?embed=y&toolbar=no&width=300&height=345&RegionParam=XXU
But is there a way to control the width and height of the resulting PNG, as well as the placement of the legend and/or source (bottom or right, etc.)?
Thanks very much, --Mel.
For .png images seems that it's a hidden parameter.
see specifying image size for tabcmd export PNG? http://community.tableau.com/message/185730
I am not sure about settings to format the legends, there are more req. on this subject on forums. I suggest you to open an idea case.