There's always a settling in period. Routine is key for ours.
Not sure why you can't have a cat flap, but if at all possible fit a magnetic one. Stops other cats coming in as well.
Don't let them dictate feeding times, they'll end up fatter than bag puss. Try different foods. One they will eat but don't like too much is better than one they really like but pester you for. Then use treats for good behaviour, medication, vet visits etc.
We stick to biscuits rather than wet food. Better for thier teeth, and stops the sometimes horrendous smell of wet food through the house. Avoid iams though. It's full of sugar, they scoff it down and throw it back up almost immediately.
Our two are no trouble at all. Only grief we have is local un neutered cats getting fiesty. Male and female cats should always be neutered. If we get any more vet bills the un neutered cats owners will be getting the bill.
We wouldn't be without ours.
