I believe that the search function goes down when there are a certain number of people connected to the boards. The search engine degrades performance, so when traffic is heavy, it is automatically disabled. At least, this is my understanding.
There is no way to definitively figure out your dining rotation before you actually check in and receive your room key, unless you are staying in a concierge suite (categories 1-3), in which case I believe you can request a specific rotation. On the 7-day cruises, your room key will have a code similar to this printed on the right-hand side:
LAPLAPL
L = Lumière's, A = Animator's Palate, P = Parrot Cay. This code tells you the order in which you'll eat at the restaurants, begining with the first night (forgive me if I'm telling you something you already know).
There are trends which allow you to make an educated guess as to which rotation you'll get. We've only ever traveled as two adults with no kids, so we always start at Lumière's (the rotation given in the example above). I'm not positive about the other two, but I believe families with younger children start at Animator's Palate (APLAPLA) and those with older kids start at Parrot Cay (PLAPLAP). I may have those two backward, though. As with any rule, there are exceptions. We're occasionally at a table with a family with kids, even with the "adults-only" rotation. A lot probably depends on the number of kids on a given cruise.
Hope this helps.