You could build an overview with an datagrid object and then use the listen to widget method to display the details of your selected object in the data grid.
If you are new to Mendix and you wants to dive in the plattform, I would suggest to have a look in the Academy section of the page. There are some very helpflull tutorials how to use Mendix.
That is definitely possible.
On creation of the Prize object you can also create any associated object. Then display these on the page for the user to fill in. On the save button of the page you can save the prize object itself and the associated objects.