@Jena45
If you are looking to host guests who stay either for a week or a month, but don't mind anything in between, then you don't need to create separate listings. You just create a minimum stay of seven nights, maximum for one month, then a weekly discount and a monthly discount. The appropriate cancellation policy will automatically apply depending on how many nights they booked (long-term cancellation policy applies for 28 days or more).
If, however, you only want one week stays and one month stays, that's a bit more complicated, but why do you want guests who stay either one week, or one month, but not guests who stay two weeks? I'm intrigued.
The other thing you should do is check tenants rights in your area. For me, in the UK, it is not a problem as I'm a live in host, so people staying with me fall into the lodger category and don't get tenants' rights, but I know it's different everywhere. You might find that once someone has stayed a month with you, it's very difficult to get them out if they decide to squat the place.