MB4 250b: Laws Regarding Acquiring Rights to a Chatzeir from a Gentile (382:3-6)

If a chatzer with only two houses (one Jew and one gentile) is connected to a chatzer (e.g. via a window) with many Jews. Does the former need an eruv?

What kind of rental is needed to be able to carry in a chatzer with a gentile - does it need to be a full-fledged rental agreement?

Do you have to specify for how long the rental is?