I do ask the fence and house question, but it's mainly 'do you rent or own' and 'do you have a fenced yard or dog run'. Renting is the main concern, in that they need to make sure it's ok to have a dog there, and make sure they aren't going to do what many do and dump the dog because they can't find a place to rent with them in a year.
The fence just so I have an idea of what the situation is, a smart person would have already thought of that and had a solution and likely would put that in their application. But if they live in the country and have no intention of doing a fence, and assume the dog will 'learn' to stay in the area around the house, then they're not getting a border collie from me.
I also ask if they plan to have children in the next 15 years, simply because some people don't get the concern there, and some think 'hey, we'll be having a baby in six months, let's get a puppy now' which of course won't work. Like other dogs, it's better to have some space between baby and puppy if possible.
Color of dog, you'll get the best pick for your home, but if you don't care what color it's different than 'really want a merle' and then there's the 'I want a split face tri with one blue eye and one brown eye and prick ears'.
All concerns, even the color if it comes up, are things to bring up and educate the person with, even if they don't like it.