Output Size and Irradiance Setting

Any advice po ba on whats good for presentation and for billboard uses with a size of 15x20 feet and 40x60 feet without blurring the image? And what values should I use on irridiance map with those sizes?

Heto gamit ko pag ganyan na kalaki yung need mo...3200 x 2400 to 7200 x 4860 with 300 DPI...yung Irridiance Map mo sa Vray gawin mong Mid or High kung kaya pa ng PC mo....Goodluck