You can enter the actual days rented, or 365 (366 for 2016).
If you will ever use one or more rooms for personal use, you may want to report them as separate rental properties. If they will always be only for rent, lumping them together is fine.
Are they rented out long-term, or short-term? Do you provide any "services", such a cleaning their rooms, meals, or concierge services? If services like that are provided, it may be a Schedule C business, rather than a Schedule E rental property.
