Yes but it is a bit less common and puts stress on was.
/gives me a rhetoric question vibe/
We tend not to put pronouns at the end. We also tend not to put verbs at the beginning or the end.
From what I know, czy ja was znam translates to "do I know you all" as was implies plural? am i wrong?
"Do I know you all?" means "Czy ja znam was wszystkich?". "You" means in Polish "ty" - sinuglar as well as "wy" what is a plural, so you don't need to use "all" to imply plural. Using "wy, was" in place of "ty, cię, ciebie" is enough.
Sorry if I'm not speaking clearly enough, I'm a Pole and I still have problems with English :)
'You all' or 'y'all' or 'you guys' are non-standard second person plural pronouns that exist in certain dialects of English. As such, 'you all' is an exact equivalent of „wy” and it's even accepted here(because at some point the decision was made to accept these everywhere in the course, as it makes sense and makes lives easier for speakers of these dialects). ;)
Wouldn't someone saying this use the formal address because he isn't sure if he knows them?
On the one hand, true. On the other, perhaps you don't exactly feel like being polite with them because they annoyed you with something. Or perhaps both you and them are young enough to stay with the informal version.