Hello sagiw,
First check out these tutorials by Greg Collins:
http://infopathdev.com/howto/tutorials/default.aspx?s=Pictures
After this I think what you are trying to do can be accomplished. You will need to make an ASPX page that returns the appropriate picture determined by one of the GET parameters passed in, then you can store those parameters in the SharePoint list and pull them down into the form in OnLoad and update the Link in the Insert Picture Control dialog box.
I hope this helps!
Matt Faus / Microsoft InfoPath MVPQdabra® Software / Streamline data gathering to turn process into knowledge