Was the back yard only fenced off because you want to Airbnb the basement?
What sort of installation have you and the landlord thought of to minimise noise for your housemates?
My inclinication is to stay yes to your housemates 5% - it keeps your relations good with those who you need on side. Why wouldn't you want to do this? It's a small amount to keep them sweet. And you are inconveniencing them.
No to offering guests access to laundry facilities (short term guests don't need them. long term can use local laundry faciliiites).
Make sure you have very clear rules on noise (include a quiet time period).
Make sure it is crystal clear to your guests that you are the host and other housemates aren't so they need to contact you directly by phone/email rather than knocking on the door, unless there is an emergency.
I am sure you have thought of this but what are you going to do if your housemates want to party or have late night noise - you can't tell them not to, because you are running a commercial enterprise in the basement.
A