Andrea,
I think you can find all the answers to your questions on the following web page.
http://digital.ni.com/public.nsf/ websearch/ 7D98C202FEC3F39086256D1E007A7609?OpenDoc ument
This document explains what features are available when communicating between PDAs and PCs and how to implement such communication.
Regards,
AlessioD
National Instruments