It's not a stupid question - but to be honest it's not really like a person going to bed, in the sense that they will often be happy to go to sleep while you are still there with TV on, lights on etc. Greyhounds and other long dogs spend a lot of time sleeping, and indeed just lying around generally!
If your dog can't settle to sleep like this it may make sense to provide him with another bed space he can go for for night times, maybe slightly away from the TV/any place there is like to be noise?
For example, mine has two beds - one under my husband's desk in the living room and one in the kitchen which is just off the living room. Under the desk is definitely his preferred space for daytime lounging (it's quite cosy and protected) but he will sometimes be in the kitchen bed when I am cooking, in the hope of getting off cuts etc!
When it gets to about 7 he will usually get up, stretch, do a big dramatic sigh to make sure we notice him and then takes himself off into the kitchen for a bit of peace and quiet!
He does sometimes just like to lie on the floor as well, either in the kitchen, lounge or hallway (these are his only choices as he isn't allowed upstairs for various reasons).
So I guess I would say, have a think - is there somewhere you definitely need him to be sleeping at night, or is it possible to allow him to choose to a certain extent? With an option to retreat from the noise if he wants to?
As he isn't house trained, I would be thinking about flooring to start with too - if there is somewhere with a wipe clean floor he might be better off in there to start with.
As he is used to kennels I wouldn't anticipate you will hear much from him in the night to be honest - he should be happy enough to be left on his own. But as you correctly say, in a way it is impossible to predict all this so an open mind is good!
Can't remember if this came up on the thread, but have you decided on house rules such as whether he is allowed on furniture, what parts of the house he is allowed in etc? Just so you can be consistent from day one.
I noticed you had been advised a lot about stealing food, but this just shows how they are all individuals - my current dog can be in the kitchen with steaks left out on the side for an hour or more and not steal them! He has an absolutely iron respect for us in terms of food, and will only eat what he has explicitly been told by is he is allowed to have (if only his respect for us in areas such as coming back when called was as great!) It just goes to show they are all individuals with their own foibles..... And all the more adorable for it in my opinion.
We've also taught him hand gestures for some commands such as sit, lie down, stay, go ahead, drop it etc, and he seems to find those easier to follow than a verbal command alone. But again I think that's specific to him rather than a long dog thing! But it's something I would advise all dog owners to at least have a try with, as it's incredibly handy if their hearing goes one day, which isn't unusual in older dogs. And it's quite a good fun thing to work on.