If Scottrade can't give you a better answer then nobody else can do better (jmo). But like I said, there will probably be a duel listing which means you won't have any problems. This topic has been talked about often in the past and we always end up in the same place. Patience is needed here on a lot of fronts.
You'll have plenty of time do figure it out between the point that Its announced and the shares are delivered. I within k it's way to early to speculate on the particulars as they are still negotiating terms apparently.
If for some reason your brokerage firm can't handle it, you can get actual paper shares and bring me somewhere else. Once they spin ST it will help as its sort of a trial run.