Yeah, I'm going to flood the floor with lights I think - I cheated and used the buydebug area lights so I wouldn't see annoying fixtures everywhere.
As for the multiple races. Here's how I do it. Between 4 and 4:30, I get them all queued up and "Go for a ride" - usually trot. Then right at 5, I queue each of them for their individual races. So far, as long as I que them at 5 or just a bit after, they all manage to ride to the center and get in their races. I had the problem you mentioned if I had them all ride to the center and then queued them up at 5 with them all standing there. They got in each other's way. This way, they tend to have time to work out the order that they go in. I get the special racing screen for each of them as well when I click on the rider.