If you're going to replace the painted cedar siding with the same siding, don't paint it. Stain the new cedar with two coats of Woodscapes stain (acrylic). Stain penetrates cedar, soaking into the wood, whereas paint mostly forms a layer on top that will eventually start peeling, requiring lots of scraping when you repaint next time. The cedar should have been stained instead of painted in the first place, but if you must paint the new cedar, which I don't recommend, you'd need to prime the bare wood with an exterior bonding primer (oil-based) that will seal the surface, and appy two coats of your Emerald exterior paint, or Duration. Duration is very durable.