Things aren't always the same in every dealership so there's no definates here but for the most part, most dealers I've worked at have at least one service "manager" (loose term sometimes) and/or service writers (sometimes one in the same). At either rate, this is sometimes complicated by a dispatcher, yet another guy who gets all the repair orders and then dispatches them to various techs depending on circumstances: requests for individual techs (yes you can do that, highly advised), how busy a tech is, whether a customer is waiting, the mood of the dispatcher (like if he's angry at a certain tech, happens), etc, etc......dealers politics.

So, in your case it's best to eventually get to know and work with one service writer who you trust and then know will go the extra mile for you and if you get to know a tech that you like and are confortable talking with, then you can and should always request that only that tech works on your car.

As for written details, if it's not written on paper, nothing more can or will be done without your permission. If you know about a specific problem, tell the writer and make sure he types it in, don't assume that the tech will just notice it and automatically repair it. The more details you mention, the better the odds of it being fixed right the first time.