You certainly do not want to ferment that high, unless you want serious bubblegum and solvent flavors! Franziskaner is a German Weissbier with a flavor balance toward clove, and weissbier yeasts throw clove flavors at lower temperatures. I'd ferment low, 60-65 degrees initially, then let the temperature rise after about half of the sugars have fermented out. As to mashing, it's likely a traditional German decoction mash, given today's malts the "Hochkurz" process. But single-infusion, it's hard to beat 152 degrees, although I might go with 150 for this beer. Step mash, use 144/156 degrees.