sweet onions are not the ones that are braided for storage. storage onions are braided and hung to dry or to use less space for in the kitchen.
don't try to braid them. they will rot.
eat them as soon as you want. they don't store long so getting sweeter as they dry won't be an issue. you cant keep them long enough to do that.
lay them out until the neck has dried out then trim them.
as for the tops... as per....
https://www.kitchengardenseeds.com/ifonion-garlic Harvesting, Curing and Storing Sweet or Pungent Globe Onions
Harvest Yellow Granex Sweet Onions as needed, any time from midsummer on, and use them within a month or two. Harvest Storage Onions a week or two after their stems have flopped over. Flopped stems signal that the plant has stopped growing and that the cherished Onions can be unearthed. If possible, harvest Onions during a stretch of dry weather. Pull them gently from the soil and handle with care to avoid bruising. Don’t remove any leaves. If the weather is dry, spread the Onions out right in the garden for a few days, but then transfer them to a warm, dry, well-ventilated place where they’ll be out of direct sunlight. A barn floor, garage floor or covered porch is good. As the Onions are curing, their leaves will gradually dry out, the neck just above the bulb will wither, and the bulb’s papery skin will be pulled tightly around the cloves. It may take up to a month for this to happen. Once the necks appear to be completely dry, use scissors or pruning shears to cut the stem about an inch above the bulb. If you can still see moisture in the stem, let the Onions cure for another week. Before storing, cull any Onion bulbs that are damaged or did not cure well. Use these up over the next couple weeks. Store the rest in mesh bags or small baskets with good ventilation. Keep them where it’s dry, dark and cool; 35 to 40 degrees F is ideal. (For next season's consideration, our favorite kitchen garden Storage Onions grown as sets include Yellow Stuttgarter, Red Wethersfield and White Ebenezer Onions. We also carry a Red, Yellow and White Onion Set Mixture for smaller-sized gardens that crave Onion diversity.)