Can we book a room without buying park passes? We have a tennis tournament nearby and simply want in spare time to sit outside at the pool

I believe you can

I'm not for sure. I just know the fee of the waterpark is included in the basic fee and I know you can go to the waterpark without staying in the resort. You should call and ask them because that particular question is about staying at the resort without using/paying for the waterpark which is unusual being that the waterpark is the main feature/reason for going to the resort.