Hello @Betty-B--M-0! I read your house rules and for the most part I think they are fine. The only thing I'm not sure of is your statement that you have "zero tolerance for behaviour that threatens our carefully nurtured environment". While I'm sure you know what those behaviours are, I would not be confident that other people would know. For example, would same sex couples, unmarried opposite sex couples, etc. be a violation of your tolerance? Keep in mind that Airbnb has just launched an anti-descrimination policy that all hosts must agree to in order to continue hosting and what you might consider intolerable might not be to Airbnb.
Unless you are willing to itemize what those behaviour are, I would remove that sentence as it is vague and one cannot anticipate what you mean.
Hope this helps!