There is formal English and there is slang. Do you know ........ ? Would be an example of formal (sometimes referred to as Proper English) You know ..........? Is an example of slang. Regional variations would also fall into this category. If you then refer to written English, then all written English should be formal, but it can include slang when written correctly. Such as using quotes or speech marks to show it is someone speaking. "Ya know Danny?!" aksed Tammy.

You can say: you know that, right? This will be more correct and you can use the interogative intonation

"you know" without the "right?" on the end usually means something different, which is not a question. You know that guy at the end of the street, he used to be a doctor before he retired. "You know" is more of an assertion than a question. Alexander's answer is good though, you know this, right?

example?