I'm sorry, but there's no way right now for FSX to load baggage/cargo from the left side, it's surely something we'll try to add in the future, because it has been requested many times, but there's no solution at the moment.
About pushback, I would be interested knowing the reason why it doesn't work with that specific airplane, and I guess we might be able to fix it from our own side too, but of course we would need to get at look at the airplane...contact me with a PM to arrange this, maybe we can fix it in time before your release.