So you kind of have more of an American Wheat recipe more so than a hefeweizen recipe although you have a hefe yeast selcted. Personally with the grains and hops selected I would use either WLP001 or WY1056 for a clean american wheat beer but YMMV
As for the mash schedule I really don't see a need to do a step mash with those grains. A single infusion at 152 will work perfectly fine. In addition, when batch sparging there is no need to do a mash out. If you wanted to do a step mash I would go with 122 for 20 minutes, 140 for 20 minutes and 152 for 20 minutes, then sparge but again YMMV