Hi there,
You are correct that some schools that are a 1 year program don't offer an internship but actually some do, for example at INSEAD if you start in January, you have an internship opp in the July/Aug whereas if you start in the Sept intake, there is no internship opp. Internships can definitely help particularly if you are trying to make a career change plus if you make an impression in an internship, you may as well have a full time offer waiting for you at the end of the school year. But it definitely doesn't mean it will be harder to find a job at the end of the school year - as you said, the majority of students who do not do an internship find employment post their MBA. It sounds like an internship is important to you so you could narrow the 1 year programs down to the schools that do offer internships. But also I wouldn't get too caught up in the fact that you can only get a job if you do an internship.
As for loans, no it is not true that it is difficult to get a loan if admitted to schools beyond the best 15. Also it really depends on the banks that you ask and which country you are in. Just ask for how much you really need (it may or may not cover living expenses). Each school will offer several scholarship opportunities so that is something you can look into as well. There are also many other kinds of loan options out there that you can look into such as
Prodigy Finance https://prodigyfinance.com/ As for visa's, there are lots of int'l students that go to the US schools so I'm sure it is possible to get one for your spouse and child. I'm afraid I don't have further details on that for you though. You can always ask the schools you are targeting as they would know.
Hope that helps. Good luck with everything.