So the context would imply more than one "you" here? So is vi good for both singular and plural of "you"?
Yes, it can be singular or plural. (And you're right, here it can only be interpreted as plural, thanks to "kune".)
So the stereotypical Southern US y'all could be translated as "vicxiu" (or v'cxiu) for Esperanto to have a more...uhhh ... precise plural hahahaha
is "vi" also a plural form of "you" like "ustedes"?