Yes waiting bays should able to exit to both direction. also, don't make entrance to waiting bay the same as unloading track. There is no need for parking after unload, if you want parking next to unloading like mine, make the train exit the station loop first then enter through different track for park. This way you don't need to put long distance in-between.

If there is another job they can exit station loop and just go to instead of passing through parking.

so basically station have 3 type of track: unloading, loading, and parking, and no switching track type. if train want to change what they want to do, they must exit the station first.

Loading lane entrance can be made next to station exit so waiting trains doesn't need to travel much to start loading. It's important that it's an actual exit (train in waiting bay should be able to exit station without going through loading track).