Creating queries

I am creating a database for venues in the US and Canada. What I would like is to set it up that users can select a state and only receive the list for that state, sorted by city. Do I have to create 50 different pages with a query for each state on it's own page or is there a way to set it up that the user selects the state and the query is created for that state?

Also when creating the Repeat Region you choose the number of rows of data that you want to display. However I often see displays where the user can choose to see more or fewer rows. Is there a way to set this up that a user can choose to see 30 or 50 or 100 rows of data?

Thanks.