score:2
Yes, the rules applies to you too. The Italian government has stated pretty clearly that all rules apply to both Italian citizens and tourists.
To be more specific, the rules for traveling in a car with non-cohabitant people are the following:
On a side note: I would double check if 5 people from 3 different households are allowed to live in the same house. I couldn't find anything specific, but I know that for visiting friends you're only allowed to have 2 people (+ kids) go to another household.