Yeast PCR and plasmid loss

I'm having trouble PCR-ing from my pGAD10 Two-Hybrid activation domain 
vector miniprepped from yeast (lots of non-specific bands and absence of 
bands in some preps). Has anyone got any suggestions for PCR-ing from 
yeast minipreps, or does it depend mainly on the primers used? Also does 
anyone know how quickly yeast lose plasmids? Is it OK to grow up yeast 
for a plasmid prep in rich media, or is it better to use selective 
media?

Thanks,
Estelle