@Michelle1648 If you're getting a lot of these kind of rule breakers, which it sounds like you are, it's not enough to just ask them how many people will be coming, etc. You have to word it in such a way that they will be afraid to break your rules. "Hi XX, Just double-checking that there will only be 5 of you coming, as stated on your booking. Arriving with extra guests or letting them in later will void my insurance and I will have to ask any unbooked guests to leave, so just want to make sure we're all clear on that, so check-in and stay will go smoothly for you."
Same kind of thing with the pets, etc. Friendly, professional, and firm about your rules.
It actually kind of sounds like the host you inherited all these guests from was really inept at vetting renters. Probably just let them all Instant Book with any messaging communication, checking their reviews, etc. You'll probably have to be really diligent with the bookings that were already made, and vet all the new renters well yourself before accepting their bookings.
And as other hosts have said, you can't just be cancelling bookings, you'll receive a barrage of penalties. Try to head off bad scenes and rule breakers through messaging, if they say they're bringing a dog, even if you don't allow pets, contact Airbnb, ask them to cancel it penalty free, looking at your message exchanges to confirm they don't want to abide by the house rules.
A lot of people think that doing an Airbnb will be an easy way to make money. It isn't. It's hard work and requires a lot of different skills. Cheers and good luck.