Q1: Yes, sure you are.
Q2: i am not really sure about it. I have never heard a plugin called nametheprice before. Can you give me a URL where i can see what "nametheprice" plugin does, a demo? By the way, is it basically a custom-field plugin? If so, yes. ClennMart and all of our templates are well compatible with 3rd party custom-field plugins (if they developed properly, of course -- if they work properly on official Virtuemart component, then they would work well on our VM3 templates as well)