Is there any way I can force a printer into duplex mode in code?

I have an app that can go to several printers, and if it goes to one that is capable of duplexing, I'd like to automatically make it duplex.

second Q: When I use REPORT FORM.....TO PRINTER PROMPT, and select more than one copy, it prints all the page1's, then all the summary pages.. is that standard? Can I change it?

Thanks in advance
Tim