I think it allow you to use one account on multiple devices. You could use the same login credentials on both locations. However, you can not view the content at the same time in 2 different locations.

If you are referring to Netflix, if your current Netflix does not allow different households, then this will continue even with STream+

It’ll depend on the individual streaming service. For example, as Netflix was mentioned, they’re trying to enforce accessing your home network at least once per 30 days.