For your first question, there are morning times and afternoon times so you won't get something in the morning that is for a time at the end of the day.
For your second question, I don't think there is a firm answer and I think it generally depends on what you are after. If there is a particular store/day combination that you absolutely must have the pins for, I suggest both trying for that. You mention trying for the earliest time but keep in mind that you might not get one at all. So by both trying for the same store you double your odds of getting into it at all. That said, if you are less picky about which store you get into, i suggest splitting it up. You still have two chances to get something, but you also now have a chance of getting both.
And if you do both try for the same store and are lucky enough to both get in the queue, keep in mind you now have room to bring two other people along with you. In that case, please keep your dear friend AJK in mind who will be all alone at D23 with nobody to help him get into shops and will be eternally grateful for assistance.